Southern California’s Premier Independent Multi-Specialty Medical & Surgical Group


About United Medical Doctors


United Medical Doctors (UMD) is dedicated to improving the health of our communities by setting the standard of excellence in specialty medical & surgical care. UMD currently offers over 30 medical & surgical specialties with over 150 providers in four Southern California counties: Riverside, Orange, San Diego & Los Angeles.

At United Medical Doctors, we specifically aim to:
· Provide the highest quality compassionate care and service for all people in the prevention, diagnosis, and treatment of medical and surgical diseases.
· Attract a team of physicians and other health care professionals of the highest moral character and greatest skill.
· Be the premier Independent Private Practice in our region with a dedication to achieving the highest levels of patient satisfaction while implementing continued process improvement.
· Provide our patients access to advanced cutting-edge specialty services by leveraging our group’s resources and close relationships and affiliations with University medical centers in the region.
· Demonstrate empathy in caring for patients which is more than just physical healing – it’s establishing a connection and trusting relationship with care that encompasses mind, body, and spirit.

Allergy | Anesthesia | Audiology | Bariatric Surgery | Cardiology | Clinical Research | Colorectal Surgery | Dermatology | Dietitian | Family Medicine | Fitness | Gastroenterology | General Surgery | Gynecology | Hepatology | Imaging | Infusion Therapy | Internal Medicine | Medical Weight Loss | Men’s Health | Neurosurgery | Oncology | Otorhinolargynology (ENT) | Orthopedic Surgery | Pain Management | Pathology | Pediatric Gastroenterology | Plastic Surgery | Podiatry | Radiology | Urgent Care | Urogynecology & Female Pelvic Health | Urology | Wound Care

UMD is proud to offer unparalleled outpatient surgical care at our Ambulatory Surgery Centers through our United Surgery Centers division: United Surgery Centers (USC). USC has locations in Temecula, Murrieta, Riverside, Newport Beach, Orange, Irvine, Mission Viejo and Encinitas.

UMD is proud to conduct clinical research that leads to advancements in medical treatment by producing high quality data retrieved in a confidential, comfortable and safe environment. United Clinical Research consists of state-of-the-art surgery centers and research sites in Riverside, San Diego and Orange Counties. We carefully and compassionately evaluate each study patient and firmly adhere to study protocol. By thoroughly planning for each study, we are able to deliver reliable and verifiable research results. Our site is fully equipped to conduct complex clinical research trials on behalf of our sponsors and our study trial participants. By providing different treatment options to best meet individual healthcare needs; not only do we offer the medicine of today, we help create the medicine of the future.


Schedule an Appointment

Scheduling an appointment is simple. We are proud to offer multiple ways to receive care, including Telemedicine visits. For new and existing patients who are scheduling an office visit or follow-up appointment , click the button below to use our Online Scheduler. Appointments are subject to insurance verification.

How We Can Help You



Medical Specialties

We proudly offer over 30 medical specialties in Southern California, ranging from ENT & Gastroenterology to Podiatry & Urgent Care.

Urgent Care

We have two state-of-the-art Urgent Care facilities in Temecula & Encinitas, proudly offering high quality urgent care with minimal wait times & comprehensive services, including rapid 15 minute COVID-19 testing.


We’re proud to offer our patients expedited lab work at our clinical lab in Temecula. We also have an anatomic pathology lab in Murrieta where all biopsy specimens are processed, delivering your results from colonoscopies & other procedures, faster.

Medical Fitness Facility

United Medical Fitness (UMF) is the only medical fitness facility in Temecula. Open to the public, UMF boasts a team of Kinesiologists, a Registered Dietitian, Personal Training, Group Classes & beyond. Check out why UMF is not your average gym, by design by scheduling a Complimentary Discovery Session today!

Surgical Specialties

Our team of skilled surgeons are proud to offer unparalleled general and sub-specialty surgical care utilizing minimally invasive & robotic techniques.

Outpatient Surgery Centers

We are proud to offer unparalleled outpatient care through our own Ambulatory Surgery Centers: United Surgery Centers (USC). USC currently has seven locations, with more in the works!
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Online Appt Scheduling

We’re proud to offer convenient ways to book an appointment with our providers. Simply click the button below!

Medical Weight Loss

With skilled Medical Weight Loss professionals, from physicians to professionals, such as a Registered Dietitian & multiple options like the Orbera Weight Loss Balloon & Bariatric Surgery, United Medical Weight Loss is eager to help you on your weight loss journey.

Telemedicine Appointments

All of our providers offer Telemedicine in addition to in-person appointments, allowing you the flexibility & freedom to choose how & when you want to receive care.

Imaging Centers

With three Imaging Centers in Southern California and growing, located in Murrieta, Temecula and Newport Beach, United Imaging Centers offers expedited imaging appointments in state-of-the-art facilities, from MRIs to CTs, Ultrasound & X-Ray.

IV Infusion Therapy

We offer IV infusion therapy at United Infusion Centers, a division of United Medical Doctors. Located in Murrieta & Los Alamitos, we specialize in infusions for specialty care to vitality infusions, in a comfortable setting.

Clinical Research

We’re proud to conduct clinical research that leads to advancements in medical treatment by producing high quality data retrieved in a confidential, comfortable & safe environment. Check out our current studies below & whether you qualify as a candidate!


We are proud to be Southern California’s premier multi-specialty medical and surgical practice with over thirty specialties to offer our patients. Ranging from audiology to urgent care, we have your specialty medical and surgical needs covered.


We are proud to announce United University of Nursing in Murrieta, CA! United Nursing College is now enrolling for their ADN to BSN program. Learn more & enroll today!


We proudly serve the counties of Riverside, Orange, San Diego and Los Angeles. View our locations and specialties below to find a specialist near you.

Your Healthcare Team


We are committed to providing the highest quality compassionate care & service for all people in the prevention, diagnosis & treatment of medical and surgical diseases.

Meet our team of providers, who strive to demonstrate empathy in caring for patients which is more than just physical healing – it’s establishing a connection and trusting relationship with care that encompasses mind, body, and spirit.

Clinical & Surgical
Medical & Surgical
Southern California
Counties Served

What Our Patients Say

Dr. Lim is my hero! Not only does she have a fun and energetic personality, she is a smart and caring doctor. She is tenacious and did not stop finding a solution for my problem. She celebrates when things are going well and is so reassuring and instills hope if there’s a setback. She is the first doctor in 30 years that listened to me and kept pushing until we had results. I am grateful I found her. She has changed my life with her expertise in medicine and her incredible bedside manner. Thank you, Dr. Lim for being you!

United Gastroenterologists | Dr. Roxanne Lim

Google Review
I came to Dr. Cai after being with another pain management doctor for 12 years, I feel like it's been one of the best changes I've ever made, she has given me injections that completely took my pain away, she checks on me by phone. With my other doctor it had gotten where I never saw him anymore, it was always a nurse practitioner. This pain management doctor and her crew are amazing, I would definitely recommend her, thank you Dr. Cai.

United Pain Center | Dr. Yi Cai

Yelp Review
I love Dr. Chen. Everything I read about him in the reviews I found to be true. He listens to you and truly cares. I was so sick and going to another Dr. that we had for almost 30 years without results. I'm so happy I found Dr Chen and I'm feeling great!

United Gastroenterologists | Dr. Philip T. Chen

Google Review
Super efficient and friendly service. You get in and get out without waiting long at all. It's also beautiful inside and very clean. The staff are constantly sanitizing. You feel safe and well taken care of here. Definitely my go-to place for my family's urgent medical needs. Thank you so much!

United Medical Doctors Urgent Care

Yelp Review
Bryan Sauter is an extremely professional PA. He takes the time to listen to his patients and works with them to come up with the best plan for their individual health care needs. He is trustworthy and motivated to find the best treatments available. I would highly recommend.

United Gastroenterologists | Bryan Sauter, PA-C

Google Review
I feel so fortunate to have found Dr. Shen. I found him to be so patient, knowledgeable and caring. Not only did he spend good quality time explaining what my symptoms could mean but several treatments available and one that gave me immediate relief. I recommend Dr. Shen to anyone that is looking for a good Gastroenterologist.

United Gastroenterologists | Dr. Huafeng Shen

Yelp Review
I think United Medical Doctors is a very excellent group of doctors! I went to the Gastroenterologists in this group! My [visit with] Dr. Saunders was excellent and very thorough! The staff was very friendly and carried out the COVID-19 rules very well! If anyone is looking for a good group of professional doctors these are the ones for you!

United Gastroenterologists | Dr. Angela Saunders

Yelp Review
Dr. Eng has been amazing! She is overwhelmingly caring and takes the time to address any issues in or out of the office. She is very knowledgeable and I'm so happy my kids and I found her!

United Gastroenterologists | Dr. Katharine Eng

Google Review
Dr. Cheng is a wonderful caring, dedicated, knowledgeable doctor. I am so happy I found him. He helped me get thru my cancer detection and I am now on my way to better health. His staff also was exceptional and caring. The entire process was actually pleasurable. Thank you Dr. Cheng.

United Oncology | Dr. Howard Cheng

Healthgrades Review
She found out what was wrong with me where 4 others didn’t! She fixed it 8 years ago and I am eternally grateful for her concern and integrity. She loves her work and it shows. Thank you!!! Thank you!! Namaste!

United Gastroenterologists | Dr. Shruti Ariza

Google Review
The staff was extremely accommodating and friendly. They were able to get an unexpected additional MRI approved by my insurance and rearranged their schedule just to accommodate me, and saved me from having to take another day off of work, due to I live in Covina. They went over and beyond my expectations and were very kind, professional and efficient. They make sure I was comfortable and got back out and on my way in record time. I really appreciate how accommodating and kind they were and will be back if I ever need more imaging in the near future. Thank you Back Bay Imaging!

United Imaging x Backbay Imaging

Yelp Review
Dr. Kim is absolutely the best Neurosurgeon, ever! He did an outstanding job performing my lumbar fusion. I have regained almost all of my nerve and muscle functions, except for the nerves that had been too severely damaged to totally heal. I feel almost as good as I did before my accident that caused these injuries. I highly recommend him if you are considering having spinal surgery, you can totally rely on his expertise to do the best procedure for you! I am so grateful to have had him as my Neurosurgeon.

United Neurosurgery | Dr. Anthony Kim

RateMDs Review

Hospital Relationships


Frequently Asked


It’s simple! You can make an appointment online below, call us at (833) UMD-DOCS or through our via our Mobile App, United MD. Contact us to receive your personalized login information for the United MD app today.

All of our specialists accept most major PPOs, Medicare and Tricare as well as some HMO insurance plans. To verify, please call our United MD Appointment Center at (833) UMD-DOCS.

Yes! We offer multiple options to receive care, including virtually through Telemedicine Appointments. We conduct our Telemedicine Appointments through our own Mobile App, United MD. Contact us to receive your personalized login information today.

Thank you for your interest in our practice and our skilled specialists! Please contact us at (833) UMD-DOCS to get set up in our system, or fill out the contact form below.

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