(650) 342-7432

100 S. Ellsworth Ave.
Suite 507
San Mateo, CA 94401
(650) 342-7432

Gastroenterologist in San Mateo, CA and surrounding Mid-Peninsula region

The brief descriptions below are designed to familiarize you with our staff's training, professional credentials and work experience.

Edward K. Onuma, MD. PhD,

Board Certified in Internal Medicine & Gastroenterology

Dr. Edward Onuma completed his undergraduate work at Cornell University and received his Ph.D. in physiology at SUNY at Buffalo, NY.  He received his medical degree at SUNY Health Science Center at Syracuse, NY in 1990.  After his internship at St. Vincent’s Hospital Medical Center in New York City, he completed his Internal Medicine residency and Gastroenterology fellowship at the Robert Wood Johnson Medical School in New Brunswick, NJ.  He then received a grant from the Japanese government to conduct research on Barrett’s esophagus at Chiba University Medical School (Chiba, Japan). While there he also received a temporary Japanese medical license and learned advanced endoscopic techniques, including techniques for the detection of flat colon polyps. Dr. Onuma has been practicing in California since 1999. He is Board Certified in Gastroenterology and is fluent in English and Japanese. He lives on the Peninsula with his wife and two sons, and enjoys hiking, photography and his new hobby of barbecuing/grilling.


Eugene Y. Lee, MD.

Board Certified in Internal Medicine & Gastroenterology

Dr. Lee graduated with honors from Columbia College of Columbia University after which he received his MD degree from NYU School of Medicine.  He completed internship and residency in Internal Medicine at the University of Rochester/Strong Memorial Hospital.  He then continued his postdoctoral training at Albert Einstein College of Medicine/Montefiore Medical Center in New York City for Gastroenterology fellowship.  Dr. Lee joined a private gastroenterology group in San Ramon, CA in 2004.  He moved to the San Mateo area in 2006.  He currently practices in all aspects of general gastroenterology and hepatology.  He has particular interest in gastroesophageal reflux, colorectal cancer, and gastrointestinal bleeding.  Dr. Lee is on the medical staff of Mills-Peninsula Hospital/Peninsula Medical Center and Mid-Peninsula Endoscopy Center.  He is a member of the AGA, ACG, ASGE, CMA, SMCMA, and CMA.  He lives on the Peninsula with his wife and two children.  He enjoys playing tennis, skiing, and discovering all the wonderful trails the Bay Area has to offer.


Office Staff

   “Lety” will likely be greeting you upon your first office visit.  She has extensive experience in medical practices and keeps the front office running smoothly.  She may also be calling you with lab results or helping to schedule appointments.  She is fluent in Spanish.
   Nanci has been with our practice for over 25 years.  And with that knowledge, she is able to make the patient experience a pleasant and fruitful one.  She also keeps Dr. Onuma on his toes!

Our newest team member, she is very efficient and organized.   And she prides herself on helping patients with anything that they need.


Office Manager

   Linda has over 20 years of experience in office bookkeeping and management.  She knows all the ins and outs of running a professional office.

Questions or Comments?
We encourage you to contact us whenever you have an interest about our services.

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100 S. Ellsworth Ave
Suite 507
San Mateo CA, 94401