Quick answers
- Which hospitals does John C. Lesniak work at?
- Medicare's official clinician data lists John C. Lesniak at 3 hospitals: Froedtert Memorial Lutheran Hospital, Oconomowoc Memorial Hospital and Waukesha Memorial Hospital. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does John C. Lesniak see patients?
- Medicare's clinician data lists 10 practice locations, including Oconomowoc, WI, Hartland, WI and Brookfield, WI. Call before your visit to confirm the address.
- What is John C. Lesniak's specialty?
- Medicare lists Family Practice as the primary specialty.
- Does John C. Lesniak accept Medicare assignment?
- Yes. Medicare's clinician data says John C. Lesniak 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 John C. Lesniak?
- (262) 928-8400, as listed in official Medicare / NPI Registry data.
- What is John C. Lesniak's NPI number?
- 1912979451. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where John C. Lesniak works
Medicare's Facility Affiliation Data lists John C. Lesniak at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Froedtert Memorial Lutheran HospitalMilwaukee, WI · Acute Care Hospital · CCN 520177
- Oconomowoc Memorial HospitalOconomowoc, WI · Acute Care Hospital · CCN 520062
- Waukesha Memorial HospitalWaukesha, WI · Acute Care Hospital · CCN 520008
Practice locations
Addresses where John C. Lesniak is enrolled with Medicare (CMS data updated 2026-10-02). The first 5 of 10; the Medicare profile lists all.
- 1185 Corporate Ctr Dr, Suite 175Oconomowoc, WI 53066 (262) 928‑8400
- 1500 Walnut Ridge DrHartland, WI 53029 (262) 928‑7500
- 195 Discovery DrBrookfield, WI 53045
- 240 Maple AveMukwonago, WI 53149 (262) 928‑1900
- 721 American AveWaukesha, WI 53188
Group practices
Medicare enrollment lists John C. Lesniak as a member of this group (CMS data updated 2026-10-02).
- Prohealth Medical Group Inc479 clinicians in the group
Specialties
- Family Practiceprimary
Other family doctors in Oconomowoc
Clinicians with the same Medicare primary specialty in Oconomowoc, WI — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Medical College Of Wisconsin |
| Graduation year | 1997 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1912979451 |
| 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