Quick answers
- Does Zachary Greenstein accept Medicare assignment?
- Yes. Medicare's clinician data says Zachary Greenstein accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- What is Zachary Greenstein's NPI number?
- 1174151872. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Zachary Greenstein works
Medicare's Facility Affiliation Data lists Zachary Greenstein at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Lenox Hill HospitalNew York, NY · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 330119
- Northern Dutchess HospitalRhinebeck, NY · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 330049
- Vassar Brothers Medical CenterPoughkeepsie, NY · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 330023
Practice locations
Addresses where Zachary Greenstein is enrolled with Medicare (CMS data updated October 2, 2026).
- 100 E 77th StNew York, NY 10075 (212) 434‑2140
- 21 Reade Pl, Suite 1000Poughkeepsie, NY 12601 (845) 214‑1821
Group practices
Medicare enrollment lists Zachary Greenstein as a member of these groups (CMS data updated October 2, 2026).
- North Shore-Lij Medical PC6,440 clinicians in the group
- Nuvance Health Medical Practice PC595 clinicians in the group
Specialties
- Internal Medicineprimary
Other internal medicine doctors in New York
Clinicians with the same Medicare primary specialty in New York, NY — not a recommendation.
Other clinicians in North Shore-Lij Medical PC
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | DO |
|---|---|
| Graduation year | 2020 (6 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1174151872 |
| 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 October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- 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