Mercedes Tomioka, M.D.

Internal Medicine

  • Affiliations: Hoag Physician Partners, Hoag Medical Group
  • Language: Spanish / Japanese

Primary Office

(949) 791-3101 (949) 791-3112

About Dr. Tomioka

A native speaker of Spanish and conversational Japanese, Dr. Tomioka brings cultural diversity, excellent skills, and her compassionate nature to her profession as a physician. Her grandparents immigrated to Peru prior to World War II and that is where Dr. Tomioka spent her early years surrounded by family, which included many physicians. Always concerned about everyone around her, her family encouraged her to become a physician to fulfill her desire to help others.

Practicing since 2003, Dr. Tomioka chose a career in Internal Medicine as she truly appreciates the challenge. She enjoys being exposed to a broad variety of skills and applying her knowledge to help her patients. She is excited to lend her talent and innovative ideas to Hoag Medical Group.

Dr. Tomioka has extensive training and always pursues ways to improve her skills and knowledge. She attended medical school at Universidad Nacional Mayor de San Marcos in Lima, Peru, completed her residency in Internal Medicine at St. Barnabas Hospital (affiliated with The New York Hospital - Cornell Medical Center), and finished with a fellowship in Geriatrics at UC Davis.

Outside of work, Dr. Tomioka enjoys spending time with her husband and daughter. Her focus is on bringing new experiences to her daughter and they often travel and visit museums during their weekend excursions.


Insurance Accepted

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Please contact your insurance provider to confirm if your health plan is accpeted.

  • Aetna - 7691697
  • Anthem - Z64420
  • Blue Shield - 100036422017
  • Cigna - 8576503040
  • Scan - 996-135989
  • United Healthcare - 0326600044

National Provider ID (NPI): 1275639262

Education &

Board Certification

  • American Board of Internal Medicine - Geriatric Medicine
  • American Board of Internal Medicine - Internal Medicine
  • Medical Education - Universidad Nacional Mayor de San Marcos (Medical Doctor)
  • Residency - National Hospital (Internal Medicine)
  • Internship - St. Barnabas Hospital (Internal Medicine)
  • Residency - St. Barnabas Hospital (Internal Medicine)
  • Fellowship - University of CA Davis Med Center (Geriatrics)


  • Hoag Physician Partners
  • Hoag Medical Group

Area of Focus

  • Internal Medicine