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

Dr. Mark T. O'Brien, DO

Individual provider Family Medicine Physician · NPI 1255322509

Dr. Mark T. O'Brien, DO is a Family Medicine Physician in Saint Clair, Michigan. Practices as a sole proprietor and works from 2 locations. Licensed in Michigan.

Licensed in
MI
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.

See every abbreviation used in this directory →

Practice location Address checks out

1280 S 9th St
Saint Clair, MI 48079-5368
Phone: (810) 326-0837
Fax: (810) 326-1534
Show map & directions

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Additional practice locations (1)

  • 4150 River Rd, East China, MI 48054-2915 — (810) 329-4660

Specialties & licences

Family Medicine Physician (primary) Taxonomy 207Q00000X · Licence 5101009744 (MI)

Record details

NPI number1255322509
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorYes
NPI enumeratedNovember 3, 2005
Last updated in NPPESFebruary 25, 2022
Certification dateFebruary 25, 2022
Mailing address1280 S 9th St, Saint Clair, MI 48079-5368

Other providers in Saint Clair