NPPES file of Aug 9, 2026

Margaret Mary Grossmayer, APRN, FNP-C

Nurse Practitioner · Willowbrook, IL

Margaret Mary Grossmayer, APRN, FNP-C is a nurse practitioner with a practice address in Willowbrook, Illinois, and NPI 1548140973, issued on Sep 5, 2025. Check the license (Illinois 209033129, as entered in NPPES) with the Illinois board that licenses this profession; the Medicare figures below come from public CMS files.

Record from CMS NPPES, file of Aug 9, 2026 · method · Verify with CMS →

NPPES recordNPPES file of Aug 9, 2026
1548140973
Name
Margaret Mary Grossmayer
Credential
APRN, FNP-C
Primary taxonomy
Nurse Practitioner 363L00000X
License number
209033129 IL
Self-reported in NPPES; status is on the state search
Practice location
40 75TH St, Willowbrook, IL 60527
Phone
(630) 581-5372
Enumerated
Sep 5, 2025
Record last updated
Nov 26, 2025
Medicare enrollment
Enrolled (PECOS I20251209002971); accepts Medicare assignment
Entity
Type 1 · individual
Public record from CMS NPPES (open it on the CMS NPI Registry). Enrollment, assignment, school and telehealth: CMS Doctors and Clinicians file, Aug 2026. A record is not a license: verify it with the state board.
Download card Updates feed

8 nearest nurse practitioner records → All 4,892 in Illinois → Look up another NPI →

Also registered at 40 75TH St

A shared address usually means a shared clinic or building; it does not show who employs whom.

  1. Noor Abutaha, APNFamily Nurse Practitioner1093456568
  2. Amy Altenberger, FNPFamily Nurse Practitioner1881374700
  3. George Antonopoulos, APRNFamily Nurse Practitioner1326660069
  4. Nimmy Baby, FNPFamily Nurse Practitioner1508502980
  5. Elizabeth BarnesNurse Practitioner1639918923
  6. Kathleen Barter, FNP-BCFamily Nurse Practitioner1225923857

Verify Margaret Mary Grossmayer in five checks

  1. 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
  2. 2LicenseActive license and public ordersWhich Illinois board licenses this profession
    Search for license 209033129    Check the board
  3. 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
  4. 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
  5. 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
Find the Illinois license search

PlainDoctor does not match the HHS-OIG exclusion list to individual records: most entries carry no NPI. Search the OIG exclusion list by name.

Is this page about you? You can ask us to correct, restrict or remove it: how.

Bills Medicare through one group practice

  1. Midwest Express Care 2, IncWillowbrook, IL

Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).

Margaret Mary Grossmayer among 4,892 nurse practitioner records in Illinois

Margaret Mary Grossmayer, APRN, FNP-C is one of 4,892 nurse practitioner records with a practice address in Illinois. 81% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2025, is newer than 92% of them.

  • NPI issued2025 · 92% of these records are older, 2% newer
  • In a Medicare fileYes · 81% of these records are
  • In the CMS Doctors and Clinicians fileYes · 69% of these records are
  • Graduated2025 · median 2018 among the 3,389 with a school on file
  • Record last updated2025 · 36% of these records were not updated in five years or more

Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 363L00000X and a Illinois practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).

22 nurse practitioner records list a practice address in Willowbrook

They are 22 of the 453 NPPES records with a practice address in Willowbrook, and 4,892 nurse practitioner records in Illinois.

All 4,892 in Illinois → Every provider in Willowbrook → Nurse Practitioner nationwide →

The 8 nurse practitioner records with the nearest ZIP codes

  1. Maria AndersonBurr Ridge, IL 605271841760535
  2. Gina Beck, ANPBurr Ridge, IL 605271407234255
  3. Jennelyn Belcina, NPWillowbrook, IL 605271427608090
  4. Nicola Bennett, APNPBurr Ridge, IL 605271942655865
  5. Linda Bond, APNBurr Ridge, IL 605271407092216
  6. Cynthia Bouffard, NPBurr Ridge, IL 605271023192432
  7. Laura Brantman-Johnson, APRNBurr Ridge, IL 605271417337247
  8. Vanessa CloudWillowbrook, IL 605271053961250

Common questions

What is Margaret Mary Grossmayer, APRN, FNP-C's NPI number?

Margaret Mary Grossmayer, APRN, FNP-C's National Provider Identifier (NPI) is 1548140973, issued on Sep 5, 2025. An NPI identifies a provider in billing; it is not a license.

Where is Margaret Mary Grossmayer, APRN, FNP-C located?

The NPPES record lists a practice address at 40 75TH St, Willowbrook, IL, 60527. Phone: (630) 581-5372. Providers update this record themselves, so call before visiting.

How can I verify Margaret Mary Grossmayer, APRN, FNP-C's license?

NPPES lists Illinois license number 209033129, as entered by the provider. Search the Illinois board that licenses this profession; the NPPES record confirms identity 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.

Written with AI tools from the named public files; every figure is computed from those files (how it is made).

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.