Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Robert I Ostroff, M.D.

Internal Medicine Physician in Petaluma, CA · enumerated 2007.

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

National Provider Identifier

1912109240

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Registry record

Entity type Individual (Type 1)

Name Robert I Ostroff

Credential M.D.

Sex Male

Practice address 400 N Mcdowell Blvd, Petaluma, CA, 94954

Phone (707) 778-1111

Enumeration date May 31, 2007

Last updated in NPPES Jul 24, 2007

Taxonomy & licenses

207R00000X Internal Medicine Physician Allopathic & Osteopathic Physicians · License G23046 (CA) 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 Robert Ostroff?

The National Provider Identifier (NPI) for Robert Ostroff is 1912109240, a Type 1 (individual) record in the CMS NPPES registry.

Where does Robert Ostroff practice?

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

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2007-07-24.