Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Mr. Gregory Zanieski, MD

Surgical Oncology Physician in New Haven, CT · enumerated 2007.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1235320474

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Registry record

Entity type Individual (Type 1)

Name Mr. Gregory Zanieski

Credential MD

Sex Male

Practice address Smilow Cancer Hospital at Yale-New Haven, 35 Park Street, 8th Floor Clinic, New Haven, CT, 06510

Phone (203) 785-3577

Fax (203) 737-4067

Enumeration date Aug 5, 2007

Last updated in NPPES Jul 30, 2019

Taxonomy & licenses

208600000X Surgery Physician Allopathic & Osteopathic Physicians · License 256848 (NY) Secondary

208600000X Surgery Physician Allopathic & Osteopathic Physicians · License MD432356 (PA) Secondary

2086X0206X Surgical Oncology Physician Allopathic & Osteopathic Physicians · License 256848 (NY) Secondary

2086X0206X Surgical Oncology Physician Allopathic & Osteopathic Physicians · License MD432356 (PA) Secondary

2086X0206X Surgical Oncology Physician Allopathic & Osteopathic Physicians · License 62463 (CT) Primary

MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

Other identifiers

Identifier	Type	State	Issuer
03227869	Medicaid	NY	-

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

What is the NPI number for Gregory Zanieski?

The National Provider Identifier (NPI) for Gregory Zanieski is 1235320474, a Type 1 (individual) record in the CMS NPPES registry.

Where does Gregory Zanieski practice?

The practice location on file with NPPES is in New Haven, CT. Providers can have multiple locations; NPPES lists the primary practice address.

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2019-07-30.