Quick answers
- Which hospitals does Gregory S. Lesser work at?
- Medicare's official clinician data lists Gregory S. Lesser at 1 hospital: Saint Michael's Medical Center. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Gregory S. Lesser see patients?
- Medicare's clinician data lists 1 practice location in Newark, NJ. Call before your visit to confirm the address.
- What is Gregory S. Lesser's specialty?
- Medicare lists Gastroenterology as the primary specialty, and also Internal Medicine.
- Does Gregory S. Lesser accept Medicare assignment?
- Yes. Medicare's clinician data says Gregory S. Lesser 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 Gregory S. Lesser?
- (973) 645-0000, as listed in official Medicare / NPI Registry data.
- What is Gregory S. Lesser's NPI number?
- 1023096575. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Gregory S. Lesser works
Medicare's Facility Affiliation Data lists Gregory S. Lesser at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Saint Michael's Medical CenterNewark, NJ · Acute Care Hospital · CCN 310096
Practice locations
Addresses where Gregory S. Lesser is enrolled with Medicare (CMS data updated 2026-10-02).
- 24 Merchant StNewark, NJ 07105 (973) 645‑0000
Group practices
Medicare enrollment lists Gregory S. Lesser as a member of this group (CMS data updated 2026-10-02).
- NJ Gastro, LLC4 clinicians in the group
Specialties
- Gastroenterologyprimary
- Internal Medicinealso
Other gastroenterologists in Newark
Clinicians with the same Medicare primary specialty in Newark, NJ — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 1999 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1023096575 |
| 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