Don J. Williams, MD
Internal Medicine Physician · Oak Park, IL
Don J. Williams, MD is an internal medicine physician with a practice address in Oak Park, Illinois, and NPI 1447288287, issued on Jun 29, 2006. Check the license (Illinois 036081395, as entered in NPPES) on the Illinois Department of Financial and Professional Regulation; the Medicare figures below come from public CMS files.
- Name
- Don J. Williams
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 036081395 IL
Self-reported in NPPES; status is on the state search - Practice location
- 1100 Lake St Ste 230, Oak Park, IL 60301
- Phone
- (331) 221-9001
- Enumerated
- Jun 29, 2006
- Record last updated
- May 19, 2022
- Fax
- (331) 221-2759
- Medicare enrollment
- Enrolled (PECOS I20060127000104); accepts Medicare assignment
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 7,238 in Illinois → Look up another NPI →
Also registered at 1100 Lake St Ste 230
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Don J. Williams in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersIllinois Department of Financial and Professional Regulation
Search for license 036081395Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
54% more Medicare Part D claims than the average internal medicine physician in 2024
4,892 Medicare Part D claims for 335 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. 174 claims were for opioids.
Most prescribed
- Atorvastatin Calcium357 claims
- Pantoprazole Sodium174 claims
- Alprazolam164 claims
- Lisinopril151 claims
- Metformin Hcl151 claims
- Gabapentin144 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The MIPS final score for 2023 (Medicare payment program): 91.4 of 100
The Merit-based Incentive Payment System score is reported for this clinician. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023; category weights for 2023 (qpp.cms.gov).
Bills Medicare through 2 group practices
- Dynamic Physical Therapy, Inc.Oak Park, IL
- Endeavor Health Medical GroupElmhurst, IL
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Don J. Williams among 7,238 internal medicine physician records in Illinois
Don J. Williams, MD is one of 7,238 internal medicine physician records with a practice address in Illinois. 73% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 7% of them.
- NPI issued2006 · 7% of these records are older, 61% newer
- In a Medicare fileYes · 73% of these records are
- In the CMS Doctors and Clinicians fileYes · 50% of these records are
- Graduated1986 · median 2003 among the 3,580 with a school on file
- Record last updated2022 · 47% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a Illinois practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
62 internal medicine physician records list a practice address in Oak Park
They are 62 of the 2,307 NPPES records with a practice address in Oak Park, and 7,238 internal medicine physician records in Illinois.
All 7,238 in Illinois → Every provider in Oak Park → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Emily Beamer, MDOak Park, IL 603011013961861
- Michele Carlon, M.D.Oak Park, IL 603011285670273
- Emelita Co, M.D.Oak Park, IL 603011396813069
- Calvin Meineke, MDOak Park, IL 603011184727539
- Steve Michel, MDOak Park, IL 603011053340695
- Bharat Parekh, M.D.Oak Park, IL 603011689610024
- Keke Uzokwe, MDOak Park, IL 603011629079488
- Janis Wiener, MDOak Park, IL 603011750315586
Common questions
What is Don J. Williams, MD's NPI number?
Don J. Williams, MD's National Provider Identifier (NPI) is 1447288287, issued on Jun 29, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Don J. Williams, MD located?
The NPPES record lists a practice address at 1100 Lake St Ste 230, Oak Park, IL, 60301. Phone: (331) 221-9001. Providers update this record themselves, so call before visiting.
How can I verify Don J. Williams, MD's license?
NPPES lists Illinois license number 036081395, as entered by the provider. Search the Illinois Department of Financial and Professional Regulation at https://idfpr.illinois.gov/checklicense.html. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Don J. Williams, MD prescribe under Medicare Part D?
In 2024, Don J. Williams, MD had 4,892 Medicare Part D claims for 335 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
What is Don J. Williams, MD's MIPS final score?
The 2023 MIPS final score is 91.4 of 100. The average among 454,083 clinicians with a measured score was 83.5.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.