Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Mark Harris Mellow, M.D.

Gastroenterology Physician in Oklahoma City, OK · enumerated 2005.

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

National Provider Identifier

1366426298

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Registry record

Entity type Individual (Type 1)

Name Dr. Mark Harris Mellow

Credential M.D.

Sex Male

Practice address 3366 Nw Expressway St, 650, Oklahoma City, OK, 73112

Phone (405) 713-4430

Fax (405) 713-4429

Enumeration date Dec 5, 2005

Last updated in NPPES Apr 2, 2014

Taxonomy & licenses

207RG0100X Gastroenterology Physician Allopathic & Osteopathic Physicians · License 14105 (OK) Primary

207RG0100X Gastroenterology Physician Allopathic & Osteopathic Physicians · License 36011 (MA) Secondary

207RG0100X Gastroenterology Physician Allopathic & Osteopathic Physicians · License 108354 (NY) Secondary

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
100019460A	Medicaid	OK	-

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 Mark Mellow's NPI record?

Cross-check NPI 1366426298 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.

Is NPI 1366426298 active?

Yes, as of the latest NPPES snapshot, NPI 1366426298 is active (record last updated 2014-04-02).

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2014-04-02.