John Hennessy, MD
John Hennessy is a Endocrinology, Diabetes & Metabolism Physician provider (Internal Medicine) practicing in Olean, NY, registered in the NPPES registry with NPI 1780676676 since 2005. The credential MD stands for Doctor of Medicine.
✓ Active NPI ✓ Valid NPI checksum
| NPI | 1780676676 |
|---|---|
| Entity type | Individual (Type 1) |
| Name | John Hennessy |
| Credential | MD |
| Sex | Male |
| Practice address | 535 MAIN ST, Olean, NY, 14760 |
| Phone | 7163720141 |
| Fax | 7163736632 |
| Enumeration date | 2005-08-17 |
| Last updated in NPPES | 2007-07-08 |
Taxonomy & licenses
| Taxonomy code | Specialty | Primary | License | State |
|---|---|---|---|---|
| 207RE0101X | Endocrinology, Diabetes & Metabolism Physician | Primary | 179364 | NY |
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 |
|---|---|---|---|
| 01139495 | Medicaid | NY | — |
Copy-ready billing details
Provider: John Hennessy, MD NPI: 1780676676 Taxonomy: 207RE0101X (Endocrinology, Diabetes & Metabolism Physician) Address: 535 MAIN ST, Olean, NY, 14760
Other providers at this practice address
| NPI | Name | Type | Specialty | Location |
|---|---|---|---|---|
| 1750380242 | Othoniel Castro | Individual | Neurology Physician | Olean, NY |
| 1386643781 | William Cihak | Individual | Internal Medicine Physician | Olean, NY |
| 1578562179 | John Balacki | Individual | Gastroenterology Physician | Olean, NY |
| 1467451658 | Ricardo Ilustre | Individual | Pediatrics Physician | Olean, NY |
| 1407855679 | Johanna Handley | Individual | Family Medicine Physician | Olean, NY |
| 1518966746 | G Spigel | Individual | Dermatology Physician | Olean, NY |
| 1598764730 | Gilbert Witte | Individual | Pulmonary Disease Physician | Olean, NY |
| 1093714230 | Fred Lewis | Individual | Allergy & Immunology Physician | Olean, NY |
Verify this record
Cross-check NPI 1780676676 against the authoritative CMS record: view John Hennessy on the official NPPES registry .
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. Read the full guide or validate an NPI number.
Frequently asked questions
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Source: CMS NPPES (public data). Snapshot 2026-07-11. Provider record last updated 2007-07-08.