Quick answers
- Which hospitals does Mark Stephen work at?
- Medicare's official clinician data lists Mark Stephen at 4 hospitals: John T Mather Memorial Hospital of Port Jefferson, Ns/Lij HS Southside Hospital, St Charles Hospital and Suny/Stony Brook University Hospital. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Mark Stephen see patients?
- Medicare's clinician data lists 2 practice locations, including Garden City, NY and Cedarhurst, NY. Call before your visit to confirm the address.
- What is Mark Stephen's specialty?
- Medicare lists Orthopedic Surgery as the primary specialty.
- Does Mark Stephen accept Medicare assignment?
- Yes. Medicare's clinician data says Mark Stephen 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 Stephen?
- (516) 536-2800, as listed in official Medicare / NPI Registry data.
- What is Mark Stephen's NPI number?
- 1790772408. 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 Stephen works
Medicare's Facility Affiliation Data lists Mark Stephen at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- John T Mather Memorial Hospital of Port JeffersonPort Jefferson, NY · Acute Care Hospital · CCN 330185
- Ns/Lij HS Southside HospitalBay Shore, NY · Acute Care Hospital · CCN 330043
- St Charles HospitalPort Jefferson, NY · Acute Care Hospital · CCN 330246
- Suny/Stony Brook University HospitalStony Brook, NY · Acute Care Hospital · CCN 330393
Practice locations
Addresses where Mark Stephen is enrolled with Medicare (CMS data updated 2026-10-02).
- 1101 Stewart Ave, Suite 100Garden City, NY 11530 (516) 536‑2800
- 123 Maple AveCedarhurst, NY 11516 (516) 536‑2800
Group practices
Medicare enrollment lists Mark Stephen as a member of this group (CMS data updated 2026-10-02).
- True North Medical Group PC188 clinicians in the group
Specialties
- Orthopedic Surgeryprimary
Other orthopedic surgeons in Garden City
Clinicians with the same Medicare primary specialty in Garden City, NY — not a recommendation.
Clinician information
| Medical school | Loyola University Of Chicago, Stritch School Of Medicine |
|---|---|
| Graduation year | 1994 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1790772408 |
| 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