William Greif, MD
NPI 1013095108 · Surgery Physician · Walnut Creek, CA
Enrolled with Medicare as Practitioner - General Surgery · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Greif, MD is a Surgery Physician provider in Walnut Creek, CA (NPI 1013095108).
Provider details
- NPI number
- 1013095108
- Entity type
- Individual
- Primary specialty
- Surgery PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- G85813 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
19 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 · 4 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Tramadol Hcl | 22 | 21 |
| Ibuprofen | 19 | 19 |
| Oxycodone Hcl | 14 | 14 |
| Ondansetronbrand: Ondansetron Odt | 12 | 12 |
Medicare Part D only. These counts cover prescriptions paid through Medicare Part D in 2024 — they do notinclude cash-pay, commercial-insurance, Medicaid, or Part B–administered drugs, and badly undercount high cash-pay categories (e.g. GLP-1 weight-loss, testosterone, and ED medications). Any drug with 10 or fewer claims is omitted by CMS, and beneficiary counts under 11 are suppressed — so a missing drug means no Part D record, never zero. This is a factual claims summary, not an endorsement, not medical advice, and not a consumer report. Source: CMS Medicare Part D Prescribers — by Provider and Drug.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-11-02
- Last updated
- 2021-12-13
Frequently asked questions
- What is William Greif's NPI number?
- William Greif's National Provider Identifier (NPI) is 1013095108, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Greif's specialty?
- William Greif is listed in the NPPES registry with a primary specialty of Surgery Physician (Allopathic & Osteopathic Physicians).
- Where is William Greif located?
- William Greif's practice location on file with NPPES is 1425 S Main St, Walnut Creek, CA 94596-5318.
- What is William Greif's phone number?
- The practice phone number listed in the NPPES registry for William Greif is (925) 295-4000.
- Does William Greif accept Medicare?
- William Greif is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Greif's NPI active?
- Yes — William Greif's NPI (1013095108) is active in the NPPES registry as of the last update on 2021-12-13.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.