Executive Officers

Taejoon Ahn, MD MPH CPE
Taejoon Ahn, MD MPH CPE
President/Chief Executive Officer

Taejoon Ahn, M.D. became the president of John Muir Medical Group (JMMG) in January of 2014. He oversees a medical group of over 300 clinicians, mostly in primary care. JMMG is the exclusive contracted provider of primary care services for John Muir Health, partnering closely for over 20 years. Prior to the presidency, Dr. Ahn served as vice president and medical director of urgent care services for JMMG. He also worked as faculty for the University of California, San Francisco's National HIV/AIDS Clinicians' Consultation Center. He is currently an Assistant Clinical Professor of Family & Community Medicine for UCSF.

Dr. Ahn also serves as director on the board of John Muir Health as well as the board of Canopy Health. Canopy Health is a joint venture between multiple provider groups to offer a large network in the San Francisco Bay Region.

Dr. Ahn received his medical degree from the University of California San Francisco, where he also completed a residency in Family & Community Medicine. He received his Masters in Public Health with an emphasis in Epidemiology from UC Berkeley. He is an alumnus of the California Healthcare Foundation's Leadership Fellowship and is a certified physician executive with the American Association for Physician Leadership (formerly the American College of Physician Executives).

Ravi Hundal, MD
Ravi Hundal, MD
Chief Financial Officer

Ravi Hundal, MD is an accomplished family physician with over 25 years of experience in the health care industry. Dr. Hundal is currently the Senior Vice President and Chief Financial Officer of John Muir Medical Group (JMMG) an organization with 300 plus physicians. As the SVP/CFO Dr. Hundal is primarily responsible for managing the company’s finances, including financial planning, management of financial risks, and financial reporting. Dr. Hundal also sits on the following boards, John Muir Health from 2013 to current, America’s Physicians Group a national medical group organization, and he chairs the John Muir Health Clinically Integrated Network/ACO Board.

His previous executive positions include, JMMG voting board member from 1999-2010, Board member of John Muir Physicians Network from 2009 to 2013, and Board member of Seven Hills School from 1999 to 2005.

Dr. Hundal received his medical degree from Autonomous University of Guadalajara, and completed his family medicine residency at Contra Costa Regional Medical Center in Martinez, CA. He also received his bachelor’s degree in Biology from the University of California Davis.

In his spare time Dr. Hundal enjoys wine, food, and traveling with his wife Dr. Marie McGlynn and spending time with his family. He also enjoys various sports including lacrosse, soccer, and hockey.

Maureen Stevenson, MD
Maureen Stevenson, MD 
Chief Operating Officer - Ambulatory Services

Maureen Stevenson, M.D. became Chief Operating Officer of John Muir Medical Ambulatory Services in January 2013. Her primary role is to provide operational oversight of all ambulatory physicians working within the John Muir Medical Group. Dr. Stevenson also provides administrative oversight of the John Muir Palliative Care program.

Dr. Stevenson has an extensive executive level background and has chaired and sat on various committees for John Muir Medical Group as well as John Muir Physicians Network and also sat on the Board of Directors for John Muir Medical Group from 2009 to 2012.

Dr. Stevenson received her medical degree from SUNY, Health Science Center at Brooklyn, New York Doctorate of Medicine, and her bachelor’s in biology from St. John’s University, Queens, New York.

Deborah Arce, MD PhD
Deborah Arce, MD PhD
Chief Operating Officer - Inpatient & Transitional Care Services

Deborah Arce, M.D., Ph.D. serves as Vice President and Chief Operating Officer of Inpatient and Transitional Care Services for John Muir Medical Group (JMMG).  Her primary role is to provide operational oversight of hospitalist programs at John Muir Medical Centers in Concord and Walnut Creek and at San Ramon Regional Medical Center.  Dr. Arce also provides administrative oversight of the Skilled Nursing Facility, Home Visit, Post-Discharge Clinic and Inpatient Palliative Care programs.  In 2018, Dr. Arce assumed responsibility for the management of the Medical Consultation Service at the John Muir Behavioral Health Center. 

Dr. Arce serves as an ex officio member of the John Muir Health Board of Directors and is a member of the Board of Directors for the John Muir Health Accountable Care Organization.  She served 3 terms on the JMMG Board of Directors.

Dr. Arce received her medical degree from the University of California, San Francisco, where she also completed a residency in Primary Care Internal Medicine.  She received a Master of Science degree from the University of California, Berkeley, and a Ph.D. from the University of California, Davis.