Quick answers
- Which hospitals does Mary Ahn work at?
- Medicare's official clinician data lists Mary Ahn at 4 hospitals: Northwestern Medicine Central Dupage Hospital, Northwestern Medicine Delnor Community Hospital, Northwestern Medicine McHenry and Northwestern Memorial Hospital. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Mary Ahn see patients?
- Medicare's clinician data lists 2 practice locations, including Winfield, IL and Glen Ellyn, IL. Call before your visit to confirm the address.
- What is Mary Ahn's specialty?
- Medicare lists General Surgery as the primary specialty.
- Does Mary Ahn accept Medicare assignment?
- Yes. Medicare's clinician data says Mary Ahn accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for Mary Ahn?
- (630) 352-5450, as listed in official Medicare / NPI Registry data.
- What is Mary Ahn's NPI number?
- 1407809056. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Mary Ahn works
Medicare's Facility Affiliation Data lists Mary Ahn at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Northwestern Medicine Central Dupage HospitalWinfield, IL · Acute Care Hospital · CCN 140242
- Northwestern Medicine Delnor Community HospitalGeneva, IL · Acute Care Hospital · CCN 140211
- Northwestern Medicine McHenryMcHenry, IL · Acute Care Hospital · CCN 140116
- Northwestern Memorial HospitalChicago, IL · Acute Care Hospital · CCN 140281
Practice locations
Addresses where Mary Ahn is enrolled with Medicare (CMS data updated 2026-10-02).
- 25 N Winfield RdWinfield, IL 60190 (630) 352‑5450
- 444 N Park BlvdGlen Ellyn, IL 60137 (630) 469‑0045
Group practices
Medicare enrollment lists Mary Ahn as a member of these groups (CMS data updated 2026-10-02).
- Northwestern Medical Faculty Foundation4,503 clinicians in the group
- Central Dupage Physician Group1,080 clinicians in the group
Specialties
- General Surgeryprimary
Other general surgeons in Illinois
Clinicians with the same Medicare primary specialty in Illinois — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Loyola University Of Chicago, Stritch School Of Medicine |
| Graduation year | 1995 |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1407809056 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians