Dorothy J. Zajac, MD
Internal Medicine Physician · Chester, IL
Dorothy J. Zajac, MD is an internal medicine physician with a practice address in Chester, Illinois, and NPI 1972592210, issued on Oct 19, 2005. Check the license on the Illinois Department of Financial and Professional Regulation; the Medicare figures below come from public CMS files.
- Name
- Dorothy J. Zajac
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 22841 WI
Self-reported in NPPES; status is on the state search - Practice location
- 1315 Lehmen Dr, Chester, IL 62233
- Phone
- (618) 826-4571
- Enumerated
- Oct 19, 2005
- Record last updated
- Jul 13, 2026
- Fax
- (618) 826-3229
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 7,238 in Illinois → Look up another NPI →
Also registered at 1315 Lehmen Dr
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Dorothy J. Zajac in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersIllinois Department of Financial and Professional RegulationCheck the board
- 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
99% fewer Medicare Part D claims than the average internal medicine physician in 2024
17 Medicare Part D claims, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D.
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.
Dorothy J. Zajac among 7,238 internal medicine physician records in Illinois
Dorothy J. Zajac, 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 2005, is newer than 0% of them.
- NPI issued2005 · 0% of these records are older, 93% newer
- In a Medicare fileYes · 73% of these records are
- In the CMS Doctors and Clinicians fileNo · 50% of these records are
- Record last updated2026 · 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).
1 internal medicine physician record lists a practice address in Chester
They are 1 of the 66 NPPES records with a practice address in Chester, and 7,238 internal medicine physician records in Illinois.
All 7,238 in Illinois → Every provider in Chester → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Alan Hagen, MDCollinsville, IL 622341114946175
- Francisco Tejada, M.D.Collinsville, IL 622341255707964
- Alberto Butalid, MDCarlyle, IL 622311023070752
- Christopher Rivera, MDCarlyle, IL 622311659372605
- Jacinta Green, M.D.Breese, IL 622301982830238
- James Wells, D.O.Breese, IL 622301992717185
- Charles Ampadu, MDSwansea, IL 622261962545269
- Alexander Bolton, D.O.Belleville, IL 622261639581127
Common questions
What is Dorothy J. Zajac, MD's NPI number?
Dorothy J. Zajac, MD's National Provider Identifier (NPI) is 1972592210, issued on Oct 19, 2005. An NPI identifies a provider in billing; it is not a license.
Where is Dorothy J. Zajac, MD located?
The NPPES record lists a practice address at 1315 Lehmen Dr, Chester, IL, 62233. Phone: (618) 826-4571. Providers update this record themselves, so call before visiting.
How can I verify Dorothy J. Zajac, MD's license?
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 Dorothy J. Zajac, MD prescribe under Medicare Part D?
In 2024, Dorothy J. Zajac, MD had 17 Medicare Part D claims; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
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.