Donald Williams, M.D.
NPI 1326043266 · Internal Medicine Physician · Whitewater, WI
Enrolled with Medicare as Practitioner - Pediatric Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Donald Williams, M.D. is a Internal Medicine Physician provider in Whitewater, WI (NPI 1326043266).
Provider details
- NPI number
- 1326043266
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- 23304 (WI)
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
21 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 · 7 distinct drugs on file.
| Drug | Part D claims (2024) |
|---|---|
| Atorvastatin Calcium | 26 |
| Levothyroxine Sodium | 22 |
| Tamsulosin Hcl | 15 |
| Sertraline Hcl | 13 |
| Amlodipine Besylate | 12 |
| Lisinopril | 12 |
| Pantoprazole Sodium | 11 |
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 , 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
- 2005-06-16
- Last updated
- 2024-05-28
- Certified
- 2024-05-28
Frequently asked questions
- What is Donald Williams's NPI number?
- Donald Williams's National Provider Identifier (NPI) is 1326043266, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Donald Williams's specialty?
- Donald Williams is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Donald Williams located?
- Donald Williams's practice location on file with NPPES is 1461 W Main St Ste B, Whitewater, WI 53190-1568.
- What is Donald Williams's phone number?
- The practice phone number listed in the NPPES registry for Donald Williams is (262) 472-6839.
- Does Donald Williams accept Medicare?
- Donald Williams is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Donald Williams's NPI active?
- Yes — Donald Williams's NPI (1326043266) is active in the NPPES registry as of the last update on 2024-05-28.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.