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Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum Sole proprietor

Dr. Maryellen O'Reilly, M.D.

General Practice Physician in Irvine, CA · enumerated 2008 · practices at Dr. Grace Guimei Yao, A Professional Corporation.

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

National Provider Identifier

1780851808

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Registry record

Entity type Individual (Type 1)
Name Dr. Maryellen O'Reilly
Credential M.D.
Sex Female
Practice address Irvine, CA, 92618
Phone (949) 586-9904
Fax (949) 586-7816
Enumeration date May 8, 2008
Last updated in NPPES May 8, 2008

Street address withheld: NPPES sole-proprietor addresses can be home addresses. See our data policy.

Taxonomy & licenses

208D00000X General Practice Physician Allopathic & Osteopathic Physicians · License G63194 (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.

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Frequently asked questions

How do I verify Maryellen O'Reilly's NPI record?
Cross-check NPI 1780851808 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.
Is NPI 1780851808 active?
Yes, as of the latest NPPES snapshot, NPI 1780851808 is active (record last updated 2008-05-08).

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2008-05-08.