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DON J WILLIAMS MD
NPI 1447288287
Internal Medicine in Oak Park, IL

Active since June 29, 2006PECOS EnrolledAccepts Medicare Assignment
91.35/100
CMS Quality Rating
1100 LAKE ST STE 230, OAK PARK, IL 60301(331) 221-9001(331) 221-2759 Get Directions Write a Review

NPPES record last updated: May 19, 2022. Verified against the NPPES registry weekly; last sync: October 25, 2026.

Record update history: May 19, 2022, Apr 27, 2021, Jan 13, 2016 (3 updates tracked since 2016).

About Don J Williams Md NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

DON J WILLIAMS MD (NPI 1447288287) is an individual internal medicine provider in Oak Park, Illinois, licensed in Illinois (036081395) and active in the NPI registry since June 2006. He is enrolled in Medicare PECOS, is affiliated with Elmhurst Memorial Hospital, and is a graduate of Other (1986).

NPPES Registry Identity

NPI1447288287
Entity TypeIndividualMale
Primary Taxonomy207R00000X
Provider Legal NameDON J WILLIAMSCredential: MD
Location Address1100 LAKE ST STE 230Oak Park, IL 60301-1095
Mailing Address4201 Winfield Rd Fl 4Warrenville, IL 60555-4025 · (331) 221-6377 · Fax (331) 221-2357
Phone(331) 221-9001
Fax(331) 221-2759
Sole ProprietorNo
Medical School CMSOtherGraduated 1986
Enumeration DateJune 29, 2006
Last NPPES UpdateMay 19, 20223 updates tracked since enumeration
NPPES CertifiedApril 27, 2021
✔ NPI 1447288287 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal MedicineAllopathic & Osteopathic Physicians
Taxonomy Code207R00000X
License✔ Licensed in IL · 036081395
Definition
A physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults and the elderly. Internists are trained in the diagnosis and treatment of cancer, infections and diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care internal medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health and effective treatment of common problems of the eyes, ears, skin, nervous system and reproductive organs.
1100 LAKE ST STE 230, Oak Park, IL 60301
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Accepted Insurance

The full list of accepted plans is on the Insurance tab. Issuers include Oscar Health.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

Don J Williams 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.

PECOS PAC ID6800800079
PECOS Enrollment IDI20060127000104
Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency✔ Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Medicare Billing Reassignments

2

Medicare enrollment records show Don Williams reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

Elmhurst Memorial Healthcare
Same address
Multi-Specialty
1100 LAKE ST, #230
Oak Park, IL 60302
  • Reassigned Medicare billing, Illinois enrollment
  • 240 clinicians in this Medicare group
NPI 1760692362 (630) 993-5676
Endeavor Health Medical Group
14 mi
Allergy & Immunology
1000 CENTRAL ST
Evanston, IL 60201
  • Reassigned Medicare billing, Illinois enrollment
  • 4,841 clinicians in this Medicare group
NPI 1497701882 (847) 570-5235

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 5

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.

Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more 99214
This is a routine check-up for patients who have previously visited our clinic. It involves a comprehensive review of your health and any ongoing treatments. The consultation lasts between 30-39 minutes, allowing enough time to discuss any concerns.
298 services127 patients
Annual wellness visit, includes a personalized prevention plan of service (pps), subsequent visit G0439
An annual wellness visit is a yearly appointment with your primary care provider to create or update a personalized prevention plan. This plan helps prevent illness based on your current health and risk factors. It's a subsequent visit, meaning it follows an initial assessment.
131 services131 patients
Administration of influenza virus vaccine G0008
The administration of the influenza virus vaccine, also known as the flu shot, is a simple procedure to protect against the flu. A healthcare provider injects a small dose of the vaccine into your arm. This stimulates your immune system to produce antibodies, which will help your body fight off the flu if exposed.
38 services37 patients
Influenza vaccine split virus, preservative free 90662
The Influenza Vaccine Split Virus, preservative-free, is a flu shot to protect against the influenza virus. It is made from parts of inactivated flu viruses and doesn't contain preservatives, reducing potential side effects. It helps your body develop immunity to the flu.
33 services32 patients
Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more 99213
This is a routine visit for patients who have already been seen by the healthcare provider. During this approximately 20-29 minute appointment, your health status will be evaluated and any necessary treatments or tests will be discussed. It's a chance to address any health concerns you may have.
16 services14 patients

Hospital Affiliations CMS Care Compare

Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.

Elmhurst Memorial Hospital

Acute Care Hospitals · Elmhurst, IL
4/5 CMS rating
OwnershipProprietary
CMS Certification Number140200
Location155 East Brush Hill RoadElmhurst, IL 60126 · Du Page County
Emergency services Birthing friendly

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 60301 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient
$138.86 typical visit price
range $60.08 – $183.39
Typical copayment $34.71 (range $15.02 – $45.84)
Most-billed visit code 99204
Established Patient
$105.70 typical visit price
range $18.97 – $148.12
Typical copayment $26.42 (range $4.74 – $37.03)
Most-billed visit code 99214
Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Medicare Quality Performance CMS QPP · MIPS

Performance in the CMS Quality Payment Program: the MIPS final score across four weighted categories, and the individual quality measures reported to Medicare.

91.35/100
MIPS Final ScoreMerit-based Incentive Payment System · CMS Quality Payment Program
Scored through an Alternative Payment Model
Quality82.71
Promoting Interoperability100
Improvement Activities40

Referred Medical Equipment & Supplies CMS DME claims 3

Durable medical equipment, devices and supplies this provider ordered from DME suppliers for patients, from Medicare fee-for-service claims.

Blood glucose test or reagent strips for home blood glucose monitor, per 50 strips A4253
DME-Other DME · category DE017N
10 suppliers27 claims77 services$6.07 avg. paid by Medicare
Lancets, per box of 100 A4259
DME-Medical/Surgical Supplies · category DA000N
6 suppliers14 claims26 services$1.13 avg. paid by Medicare
Supply allowance for therapeutic continuous glucose monitor (cgm), includes all supplies and accessories, 1 month supply = 1 unit of service K0553
DME-Other DME · category DE017N
2 suppliers11 claims11 services$171.11 avg. paid by Medicare
Dollar amounts are the average Medicare paid the supplier per service. They are not the cost to the patient.

Other Providers at the Same Location NPPES 9

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

DR. ELIZABETH M MATHEW MD
Family Medicine
1100 LAKE ST STE 230
OAK PARK, IL 60301
Cook County (331) 221-9001
DR. MARY C HUTTON MD
Family Medicine
1100 LAKE ST STE 230
OAK PARK, IL 60301
Cook County (331) 221-9001
IDA NESSA AHMADY DO
Family Medicine
1100 LAKE ST STE 230
OAK PARK, IL 60301
Cook County (331) 221-9001
TERESA SMITH LCSW
Social Worker (Clinical)
1100 LAKE ST STE 230
OAK PARK, IL 60301
Cook County (630) 646-7047
COLLEEN M WEILER D.O.
Family Medicine
1100 LAKE ST STE 230
OAK PARK, IL 60301
Cook County (331) 221-9001
RAFAEL ALEJANDRO TORRES MD
Family Medicine
1100 LAKE ST STE 230
OAK PARK, IL 60301
Cook County (331) 221-9001
FORREST JAMES ROBINSON DO
Family Medicine
1100 LAKE ST STE 230
OAK PARK, IL 60301
Cook County (331) 221-9001
KATHERINE D LYNCH MD
Family Medicine
1100 LAKE ST STE 230
OAK PARK, IL 60301
Cook County (331) 221-9001

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 Don Williams's NPI number?

The NPI number for Don Williams is 1447288287. It was assigned to this individual provider in the NPPES registry on June 29, 2006.

Where is Don Williams located?

Don Williams practices at 1100 Lake St Ste 230, Oak Park, IL 60301. The listed phone number is (331) 221-9001.

What is Don Williams's specialty?

The primary specialty registered for this NPI is Internal Medicine with taxonomy code 207R00000X.

Is Don Williams enrolled in Medicare?

Yes. Don Williams 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 Don Williams's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Don Williams reassigns Medicare benefits to 2 organizations: Elmhurst Memorial Healthcare (Oak Park, IL) and Endeavor Health Medical Group (Evanston, IL). 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 Don Williams's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

What insurance does Don Williams accept?

Health plans from Oscar Health list Don Williams 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 Don Williams affiliated with any hospitals?

According to CMS data, Don Williams is affiliated with Elmhurst Memorial Hospital.

When was this NPI record last updated?

The NPPES record for Don Williams was last updated on May 19, 2022. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 4 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.