William M. Greif, MD
William M. Greif is a Surgery Physician provider (Surgery) practicing in Walnut Creek, CA, registered in the NPPES registry with NPI 1013095108 since 2006. The credential MD stands for Doctor of Medicine.
✓ Active NPI ✓ Valid NPI checksum
| NPI | 1013095108 |
|---|---|
| Entity type | Individual (Type 1) |
| Name | William M. Greif |
| Credential | MD |
| Sex | Male |
| Practice address | 1425 S MAIN ST, Walnut Creek, CA, 94596 |
| Phone | 9252954000 |
| Enumeration date | 2006-11-02 |
| Last updated in NPPES | 2021-12-13 |
Taxonomy & licenses
| Taxonomy code | Specialty | Primary | License | State |
|---|---|---|---|---|
| 208600000X | Surgery Physician | Primary | G85813 | CA |
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 |
|---|---|---|---|
| 00G858130 | Medicaid | CA | — |
Copy-ready billing details
Provider: William Greif, MD NPI: 1013095108 Taxonomy: 208600000X (Surgery Physician) Address: 1425 S MAIN ST, Walnut Creek, CA, 94596
Other providers at this practice address
| NPI | Name | Type | Specialty | Location |
|---|---|---|---|---|
| 1578565198 | Sari Fredrickson | Individual | Adult Health Nurse Practitioner | Walnut Creek, CA |
| 1265424113 | Linda Rollins | Individual | Adult Health Nurse Practitioner | Walnut Creek, CA |
| 1902890114 | Jacqueline Alkire | Individual | Adult Health Nurse Practitioner | Walnut Creek, CA |
| 1609858802 | Audrey Nagle | Individual | Neonatal-Perinatal Medicine Physician | Walnut Creek, CA |
| 1427031335 | Dennis Fua | Individual | Anesthesiology Physician | Walnut Creek, CA |
| 1396715538 | Sharyn Ginsberg | Individual | Women's Health Nurse Practitioner | Walnut Creek, CA |
| 1770554693 | Brian Baskin | Individual | Emergency Medicine Physician | Walnut Creek, CA |
| 1386615151 | Diane Seipel Sherard | Individual | Nurse Practitioner | Walnut Creek, CA |
Verify this record
Cross-check NPI 1013095108 against the authoritative CMS record: view William M. Greif on the official NPPES registry .
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. Read the full guide or validate an NPI number.
Frequently asked questions
What is the NPI number for William Greif?
Where does William Greif practice?
Source: CMS NPPES (public data). Snapshot 2026-07-11. Provider record last updated 2021-12-13.