Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Gregory P Duff, M.D.

Orthopaedic Surgery Physician in Silverdale, WA · enumerated 2006.

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

National Provider Identifier

1952374290

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Registry record

Entity type Individual (Type 1)

Name Gregory P Duff

Credential M.D.

Sex Male

Practice address 4409 Nw Anderson Hill Rd, Silverdale, WA, 98383

Phone (360) 698-6630

Fax (360) 825-6536

Enumeration date Feb 8, 2006

Last updated in NPPES Dec 2, 2020

Taxonomy & licenses

207X00000X Orthopaedic Surgery Physician Allopathic & Osteopathic Physicians · License MD00034439 (WA) 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
1105137	Medicaid	WA	-
1023009	Medicaid	WA	-
0199377	Other	WA	LABOR AND INDUSTRIES

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 specialty is Gregory Duff?

Gregory Duff is registered in NPPES with the primary taxonomy of Orthopaedic Surgery Physician. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

Is this the official NPI registry?

No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2020-12-02.