Doctor profile · Federal record
Dr. Margaret Williamson, MD
Emergency Medicine Physician (CMS: Emergency Medicine) · Emergency Medicine Physician · Oak Lawn, IL
- NPI 1154514867
- Accepts Medicare
- 19 yrs in practice
- Female
- Group practice
- No sanctions
Practice & contact
Operates at 2 locations .
- Primary practice
-
4440 W 95Th St
Oak Lawn, IL 604532600
(434) 466-2969 - Additional location
-
211 E Ontario St Ste 200
Chicago, IL 606113284
(312) 694-7000
fax (312) 926-6274 - Mailing address
-
29373 Network Pl
Chicago, IL 606731293
Credentials & registration
- NPI registered
- August 2007 — 19 yrs on file
- Profile last updated
- March 12, 2024
- Year of graduation
- 2007 — 19 yrs since
- Specialty taxonomy
- 207P00000X — NUCC code
- State licenses (2)
- Illinois #036126342 · Illinois #125-052545
Federal sanctions & exclusions
No sanctions, exclusions or revocations on file
Checked against OIG LEIE on NPI 1154514867. Last verified May 11, 2026.Medicare procedures · 2023
Top services delivered
Total services
362
Distinct HCPCS
4
Medicare allowed
$60,360
| HCPCS | Description | Services | Patients | Avg allowed | |
|---|---|---|---|---|---|
99285 |
Emergency department visit with high level of medical decision making | 220 | 214 | $189 | |
99284 |
Emergency department visit with moderate level of medical decision making | 103 | 102 | $130 | |
99283 |
Emergency department visit with low level of medical decision making | 22 | 22 | $78 | |
99291 |
Critical care, first 30-74 minutes | 17 | 17 | $216 |
In context: peer comparison
Among 49 peers in Oak Lawn Emergency Medicine Physician, average services per provider: 79. This provider delivers 4.6× the peer median.Frequently asked questions
What is Dr. Margaret Williamson's medical specialty?
Dr. Margaret Williamson practices Emergency Medicine Physician in Oak Lawn, IL.
Where does Dr. Margaret Williamson practice?
Dr. Margaret Williamson practices at 4440 W 95Th St, Oak Lawn, IL 604532600. Office phone: 4344662969.
What is Dr. Margaret Williamson's NPI?
Dr. Margaret Williamson's National Provider Identifier (NPI) is 1154514867, issued by NPPES.
Does Dr. Margaret Williamson accept Medicare assignment?
Yes. Dr. Margaret Williamson accepts Medicare assignment, meaning Medicare-allowed amounts are accepted as full payment for covered services.
What procedures does Dr. Margaret Williamson commonly perform?
Top Medicare-reported procedures in 2023: Emergency department visit with high level of medical decision making (HCPCS 99285); Emergency department visit with moderate level of medical decision making (HCPCS 99284); Emergency department visit with low level of medical decision making (HCPCS 99283). Source: CMS Medicare Physician & Other Practitioners file.