Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.
NPIDirectory

Mark C O'Brien, DO

Individual provider Internal Medicine Physician · NPI 1497744247

Mark C O'Brien, DO is an Internal Medicine in Vista, California. Graduated from Michigan State University College of Osteopathic Medicine in 1987, 39 years ago. Accepts Medicare assignment and offers telehealth. Licensed in California.

Years since qualifying
39
Trained at
Michigan State University College of Osteopathic Medicine
Licensed in
CA
In the registry since
2005
What do these letters mean?
DO — Doctor of Osteopathic Medicine
A fully licensed physician, trained like an MD with additional musculoskeletal training. Equivalent practice rights in all 50 states.

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Practice location Address checks out

161 Thunder Dr Ste 210
Vista, CA 92083-6052
Phone: (760) 216-6500
Fax: (760) 295-4753
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Internal Medicine Physician (primary) Taxonomy 207R00000X · Licence 20A6017 (CA)

Record details

NPI number1497744247
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorNo
NPI enumeratedOctober 14, 2005
Last updated in NPPESApril 1, 2025
Certification dateApril 1, 2025
Mailing address161 Thunder Dr Ste 210, Vista, CA 92083-6052

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyINTERNAL MEDICINE
Medical schoolMICHIGAN STATE UNIVERSITY COLLEGE OF OSTEOPATHIC MEDICINE
Graduated 1987 (39 years in practice)
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services

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