About Cornerstone Primary Care


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Meet Dr. Pirkle

Board-certified internal medicine specialist Ross Pirkle, MD, MS, serves as a physician and advocate for patients at Cornerstone Primary Care in Walnut Creek, California. 

With degrees from the University of California, Berkeley and the University of California, San Francisco, Dr. Pirkle has practiced medicine in the Walnut Creek area and John Muir Hospital for 2 decades. He served as chief of medicine at John Muir Medical Center for two terms, where he remains a leader in the medical community.

Dr. Pirkle helps women and men navigate the vast and sometimes overwhelming health care system and can call upon relationships that he maintains with professors of medicine at UCSF, Stanford and even the Mayo Clinic. He finds great joy in practicing internal medicine and uses all his scientific knowledge to help patients achieve optimal health. 

Dr. Pirkle empowers patients to achieve their health goals and believes in using a combination of therapies, including Acupuncture, behavioral health, body work, or Chiropractic, along with Traditional Medicine, to create wellness.

For patients looking for a doctor who is on their side when it comes to better health, contact Dr. Pirkle at Cornerstone Primary Care.

Ready to find out more?

Call 925-378-4040 to schedule your appointment today!

Dr. Robert Hardy

Ready to find out more?

Call 925-378-4040 to schedule your appointment today!

Meet Dr. Hardy

Joining Cornerstone Primary Care as a new associate is Robert A. Hardy, MD who is board certified in Internal Medicine and is a Clinical Professor at the University of California, San Francisco School of Medicine.  Dr. Hardy is well known and widely respected in the professional community, having held leadership roles in organized medicine at the local, state and national levels.  He has worked with the California Medical Association in developing a five-year health plan for the State and more recently in defining health care policy and improved quality care for Californians during the ongoing pandemic.

A native midwesterner, Dr. Hardy took his undergraduate degree at the University of Illinois, earned his medical degree at Baylor College of Medicine, completed residency training programs at both the University of California, Davis and the University of California, San Francisco and subspecialty fellowship training at the University of Chicago.  He has held faculty positions at both the University of California, Davis and the University of Chicago, has served as a consultant physician to Veterans Administration Medical Centers in northern California and has served as department chair for both John Muir Medical Center-Walnut Creek and for the Contra Costa County Regional Medical Center.  He has also received awards from San Francisco General Hospital for excellence in patient care and recognition from the Center for the Study of Diseases as a “Top Doctor” among all Bay Area physicians.

As a clinician-scientist Dr. Hardy has published several articles in the peer-reviewed medical literature and has written a chapter in the world’s most widely published specialty textbook, this translated into nearly one-hundred languages.  His publications include reports of novel infectious diseases in women and advanced imaging studies for valvular heart disease.  Dr. Hardy’s research work has included determining the earliest manifestations of diabetes mellitus, monitoring medications associated with blinding eye disease, developing novel treatments for target organ diseases and involvement in post-marketing studies of prescription medications.  He has been actively involved in medical teaching for more than two decades and has received prestigious awards in this regard at the University of California, San Francisco School of Medicine; many of the medical students, resident physicians and fellows with whom he has worked have themselves gone on to successful medical careers and taken academic faculty positions at medical schools across the United States.

Outside of his busy and enjoyable career Dr. Hardy enjoys time with his adult children, two young grandchildren and a wide range of recreational sports activities that includes middle-distance running, mountain biking, whitewater rafting and open-water swimming.  His hobby interests include cultivation of native California plants and restoration of historic adobe homes in the local area.

Dr. Hardy brings a passion for considerate, compassionate care and a wealth of experience to our membership practice, and he is seeing new patients in our Walnut Creek office.  If you, family members or friends are looking for excellence in primary care medicine, do visit our website for more information and then call or email our office for an appointment

Ready to find out more?

Call 925-378-4040 to schedule your appointment today!

We take a human-centered approach to setting appointments to help you get the care you need when you need it.

We also have same-day appointments!

Please call us at 925-378-4040 to schedule your appointment today!

Call for appointment 925-937-4040

Dr Pirkle is everything I would want in an internist: exacting, accurate, kind and current. My medical care has been a team sport. Dr Pirkle has lead and formed that team. I have never been disappointed in a specialist Dr Pirkle has recommended. I believe quality medical care all starts and ends with an excellent internist, otherwise there is no cohesion. I highly recommend Dr Ross Pirkle.

-Bill C.

What I love about Dr Pirkle is that he takes the time to understand the problem. I never feel rushed. He is thorough and caring and provides reminders about getting vaccines and other tests with other Specialists. The staff is friendly and responsive and will get you an appt quickly if necessary. So glad I switched to his practice!

-Therese W.

My experience with Dr. Pirkle has been excellent. It was recommended that I see him many years ago. He persisted with testing until the problem was diagnosed and the solutions found. He did some extra work on the treatment of this unusual (at the time) disease and sent lots of info to me to help with the dietary treatment. Since then he has been supportive and available to me in the hospital and the office. I highly recommend him to anyone.

-Ellen P.