DR. WILLIAM B GREGORY MD
NPI 1659337350
Emergency Medicine in Pasadena, CA
About Dr. William B Gregory Md NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
DR. WILLIAM B GREGORY MD (NPI 1659337350) is an individual emergency medicine provider in Pasadena, California, licensed in California (A78714) and active in the NPI registry since April 2006. He is enrolled in Medicare PECOS, is affiliated with Northern Nevada Medical Center, and is a graduate of Medical University Of South Carolina College Of Medicine (1999).
NPPES Registry Identity
Specialties & Licenses
Other Identifiers 4
Accepted Insurance
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
Dr. William B Gregory Md is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Medicare Billing Reassignments
13Medicare enrollment records show William Gregory reassigns Medicare billing to 13 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Sparks, NV 89434
- Reassigned Medicare billing, Nevada enrollment
- 44 clinicians in this Medicare group
Sparks, NV 89434
- Reassigned Medicare billing, Nevada enrollment
- 117 clinicians in this Medicare group
Winnemucca, NV 89445
- Reassigned Medicare billing, Nevada enrollment
- 32 clinicians in this Medicare group
San Antonio, TX 78229
- Reassigned Medicare billing, Texas enrollment
- 1,452 clinicians in this Medicare group
San Antonio, TX 78249
- Reassigned Medicare billing, Texas enrollment
- 379 clinicians in this Medicare group
Killeen, TX 76549
- Reassigned Medicare billing, Texas enrollment
- 387 clinicians in this Medicare group
Dallas, TX 75246
- Reassigned Medicare billing, Texas enrollment
- 1,044 clinicians in this Medicare group
Bonham, TX 75418
- Reassigned Medicare billing, Texas enrollment
- 48 clinicians in this Medicare group
Edinburg, TX 78539
- Reassigned Medicare billing, Texas enrollment
- 257 clinicians in this Medicare group
Mcallen, TX 78503
- Reassigned Medicare billing, Texas enrollment
- 170 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Areas of Expertise CMS Part B claims 4
Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.
Hospital Affiliations CMS Care Compare 3
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
Northern Nevada Medical Center
Acute Care Hospitals · Sparks, NVTmc- Bonham Hospital
Critical Access Hospitals · Bonham, TXBaylor Scott And White Emergency Hospital
Acute Care Hospitals · Burleson, TXPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 91105 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Other Providers at the Same Location NPPES 20
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
PASADENA, CA 91105
PASADENA, CA 91105
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is William Gregory's NPI number?
The NPI number for William Gregory is 1659337350. It was assigned to this individual provider in the NPPES registry on April 22, 2006.
Where is William Gregory located?
William Gregory practices at 100 W California Blvd, Pasadena, CA 91105. The listed phone number is (626) 397-3445.
What is William Gregory's specialty?
The primary specialty registered for this NPI is Emergency Medicine with taxonomy code 207P00000X.
Is William Gregory enrolled in Medicare?
Yes. William Gregory is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Which organizations bill Medicare for William Gregory's services?
According to the CMS Revalidation Reassignment List (October 2026 release), William Gregory reassigns Medicare benefits to 13 organizations: Edwards Bell MD PC (Sparks, NV), Sound Physicians Emergency Medicine Of Nevada Bessler PLLC (Sparks, NV), Winnemucca Emergency Physicians LLC (Winnemucca, NV), Emergency Medicine Services Of Tx, PLLC (San Antonio, TX), Third Coast Emergency Physicians Southwest PA (San Antonio, TX) and 8 more organizations, listed in the Medicare section above. Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for William Gregory's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
What insurance does William Gregory accept?
Health plans from Baylor Scott and White Health Plan, Blue Cross and Blue Shield of Texas, Molina Healthcare, Oscar Insurance Company and UnitedHealthcare list William Gregory as in-network in at least one marketplace plan. Coverage varies by plan and year; verify with the insurer or the provider before a visit.
Is William Gregory affiliated with any hospitals?
According to CMS data, William Gregory is affiliated with Northern Nevada Medical Center, Tmc- Bonham Hospital and Baylor Scott And White Emergency Hospital.
When was this NPI record last updated?
The NPPES record for William Gregory was last updated on June 13, 2008. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 18 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.
# Dr. William B Gregory, MD · NPI 1659337350
Emergency Medicine physician in Pasadena, California. Individual provider, active in the CMS NPPES registry since April 22, 2006.
## Identity
- **NPI:** 1659337350 (Entity type: Individual)
- **Enumerated:** April 22, 2006
- **Primary specialty:** Emergency Medicine · taxonomy 207P00000X
- **State license:** A78714 (California)
- **Sole proprietor:** No
## Practice location
- **Address:** 100 W CALIFORNIA BLVD, Pasadena, CA 91105-3010
- **Phone:** (626) 397-3445 · **Fax:** (626) 397-5643
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 13 organizations under Medicare reassignment (form CMS-855R): Edwards Bell MD PC (NPI 1740157098, Sparks, NV); Sound Physicians Emergency Medicine Of Nevada Bessler PLLC (NPI 1881151231, Sparks, NV); Winnemucca Emergency Physicians LLC (NPI 1770532640, Winnemucca, NV); Emergency Medicine Services Of Tx, PLLC (NPI 1245938729, San Antonio, TX); Third Coast Emergency Physicians Southwest PA (NPI 1497793475, San Antonio, TX); and 8 more · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Medical University Of South Carolina College Of Medicine, class of 1999
## Record status
- **NPPES last updated:** June 13, 2008
- **Other identifiers:** Medicare UPIN H89495; Medicare PIN WA78714C (CA); Medicare PIN WA78714D (CA); and 1 more
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Source: [NPI Profile](https://npiprofile.com/npi/1659337350) · Data from the CMS NPPES public registry.