Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Robert C Mcmahon, OD

Optometrist in Winona, MN · enumerated 2006 · practices at Gundersen Clinic, Ltd..

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

National Provider Identifier

1598711400

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Registry record

Entity type Individual (Type 1)

Name Robert C Mcmahon

Credential OD

Sex Male

Practice address 106 E 2nd St, Winona, MN, 55987

Phone (507) 454-4640

Enumeration date May 25, 2006

Last updated in NPPES Jul 8, 2007

Taxonomy & licenses

152W00000X Optometrist Eye and Vision Services Providers · License 1471 (MN) Primary

OD · Doctor of Optometry: A licensed optometrist providing primary vision care, eye exams, and corrective lenses. About the OD credential

Other identifiers

Identifier	Type	State	Issuer
38629600	Medicaid	WI	-

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

How do I verify Robert Mcmahon's NPI record?

Cross-check NPI 1598711400 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.

Is NPI 1598711400 active?

Yes, as of the latest NPPES snapshot, NPI 1598711400 is active (record last updated 2007-07-08).

Other providers at this practice address

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Gundersen Clinic, Ltd. Optometrist · Winona, MN NPI 1114971751 Bradlee Wolner Optometrist · Winona, MN NPI 1356395024

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2007-07-08.