Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Mary Margaret Oneill, CFNP
Nurse Practitioner in Adelphi, MD · enumerated 2006.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1841374261
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Registry record
Entity type Individual (Type 1)
Name Mary Margaret Oneill
Credential CFNP
Sex Female
Practice address 1801 Metzerott Road, Adelphi, MD, 20783
Phone (301) 434-0500
Fax (301) 434-1962
Enumeration date Oct 24, 2006
Last updated in NPPES Jul 8, 2007
Taxonomy & licenses
363L00000X Nurse Practitioner Physician Assistants & Advanced Practice Nursing Providers · License AC000300 (MD) Primary
363L00000X Nurse Practitioner Physician Assistants & Advanced Practice Nursing Providers · License 0024129639 (VA) Secondary
Other identifiers
| Identifier | Type | State | Issuer |
|---|---|---|---|
| P00297838 | Other | - | RR MEDICARE |
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.
Frequently asked questions
Where does Mary Oneill practice?
The practice location on file with NPPES is in Adelphi, MD. Providers can have multiple locations; NPPES lists the primary practice address.
What is the NPI number for Mary Oneill?
The National Provider Identifier (NPI) for Mary Oneill is 1841374261, a Type 1 (individual) record in the CMS NPPES registry.
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2007-07-08.