Maria O'Brien, M.D.
NPI 1366429011 · Family Medicine Physician · Leonardtown, MD
Enrolled with Medicare as Practitioner - Family Practice · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Maria O'Brien, M.D. is a Family Medicine Physician provider in Leonardtown, MD (NPI 1366429011).
Provider details
- NPI number
- 1366429011
- Entity type
- Individual
- Primary specialty
- Family Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Female
- Sole proprietor
- No
- License
- 25649 (AL)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
20 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
1 documented practice location
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 9 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 33 | 22 |
| Amlodipine Besylate | 23 | 15 |
| Levothyroxine Sodium | 22 | 16 |
| Omeprazole | 17 | 16 |
| Losartan Potassium | 15 | 12 |
| Rosuvastatin Calcium | 14 | 11 |
| Metformin Hcl |
Practice location
Mailing address
Registry dates
- Enumerated
- 2005-12-23
- Last updated
- 2017-01-24
Frequently asked questions
- What is Maria O'Brien's NPI number?
- Maria O'Brien's National Provider Identifier (NPI) is 1366429011, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Maria O'Brien's specialty?
- Maria O'Brien is listed in the NPPES registry with a primary specialty of Family Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Maria O'Brien located?
- Maria O'Brien's practice location on file with NPPES is 41680 Miss Bessie Dr Ste 301, Leonardtown, MD 20650-2965.
- What is Maria O'Brien's phone number?
- The practice phone number listed in the NPPES registry for Maria O'Brien is (301) 997-0055.
- Does Maria O'Brien accept Medicare?
- Maria O'Brien is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Maria O'Brien's NPI active?
- Yes — Maria O'Brien's NPI (1366429011) is active in the NPPES registry as of the last update on 2017-01-24.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.