Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. William P Brennan, MD

Cardiovascular Disease Physician in Olympia, WA · enumerated 2005.

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

National Provider Identifier

1487655858

Verified

See something wrong? Report a correction

Registry record

Entity type Individual (Type 1)

Name Dr. William P Brennan

Credential MD

Sex Male

Practice address 500 Lilly Rd Ne, Ste 100, Olympia, WA, 98506

Phone (360) 413-8525

Fax (360) 913-8876

Enumeration date Aug 9, 2005

Last updated in NPPES Apr 23, 2021

Taxonomy & licenses

207RI0011X Interventional Cardiology Physician Allopathic & Osteopathic Physicians · License 22987 (WA) Secondary

207RC0000X Cardiovascular Disease Physician Allopathic & Osteopathic Physicians · License MD00022987 (WA) Primary

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

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 → Validate an NPI →

Frequently asked questions

What is the NPI number for William Brennan?

The National Provider Identifier (NPI) for William Brennan is 1487655858, a Type 1 (individual) record in the CMS NPPES registry.

Where does William Brennan practice?

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

Other providers at this practice address

Browse all →

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2021-04-23.