Quick answers
- Which hospitals does Mark S. Ostrem work at?
- Medicare's official clinician data lists Mark S. Ostrem at 3 hospitals: Beth Israel Deaconess Hospital - Milton, Brigham and Women Faulkner Hospital and South Shore Hospital. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Mark S. Ostrem see patients?
- Medicare's clinician data lists 1 practice location in Pembroke, MA. Call before your visit to confirm the address.
- What is Mark S. Ostrem's specialty?
- Medicare lists Internal Medicine as the primary specialty, and also Geriatric Medicine.
- Does Mark S. Ostrem accept Medicare assignment?
- Yes. Medicare's clinician data says Mark S. Ostrem accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for Mark S. Ostrem?
- (781) 202-9292, as listed in official Medicare / NPI Registry data.
- What is Mark S. Ostrem's NPI number?
- 1811985633. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Mark S. Ostrem works
Medicare's Facility Affiliation Data lists Mark S. Ostrem at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Beth Israel Deaconess Hospital - MiltonMilton, MA · Acute Care Hospital · CCN 220108
- Brigham and Women Faulkner HospitalJamaica Plain, MA · Acute Care Hospital · CCN 220119
- South Shore HospitalSouth Weymouth, MA · Acute Care Hospital · CCN 220100
Practice locations
Addresses where Mark S. Ostrem is enrolled with Medicare (CMS data updated 2026-10-02).
- 15 Old W Elm StPembroke, MA 02359 (781) 202‑9292
Group practices
Medicare enrollment lists Mark S. Ostrem as a member of this group (CMS data updated 2026-10-02).
- Pembroke Medical Associates Inc26 clinicians in the group
Specialties
- Internal Medicineprimary
- Geriatric Medicinealso
Other internal medicine doctors in Pembroke
Clinicians with the same Medicare primary specialty in Pembroke, MA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Minnesota Medical School |
| Graduation year | 1976 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1811985633 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians