Quick answers
- Which hospitals does Mark E. Lassise work at?
- Medicare's official clinician data lists Mark E. Lassise at 5 hospitals: Madison County Health Care System, Mercy Medical Center-New Hampton, MercyOne Oelwein Medical Center, Mitchell County Regional Health and Regional Health Services of Howard County. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Mark E. Lassise see patients?
- Medicare's clinician data lists 3 practice locations, including Mason City, IA, New Hampton, IA and Forest City, IA. Call before your visit to confirm the address.
- What is Mark E. Lassise's specialty?
- Medicare lists Psychiatry as the primary specialty.
- Does Mark E. Lassise accept Medicare assignment?
- Yes. Medicare's clinician data says Mark E. Lassise 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.
- Does Mark E. Lassise offer telehealth?
- Medicare's clinician data says Mark E. Lassise offers telehealth services. Ask the office which visits can be done by video or phone.
- What is the phone number for Mark E. Lassise?
- (641) 394-4121, as listed in official Medicare / NPI Registry data.
- What is Mark E. Lassise's NPI number?
- 1023002508. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Mark E. Lassise works
Medicare's Facility Affiliation Data lists Mark E. Lassise at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Madison County Health Care SystemWinterset, IA · Critical Access Hospital · CCN 161326
- Mercy Medical Center-New HamptonNew Hampton, IA · Critical Access Hospital · CCN 161331
- MercyOne Oelwein Medical CenterOelwein, IA · Critical Access Hospital · CCN 161338
- Mitchell County Regional HealthOsage, IA · Critical Access Hospital · CCN 161323
- Regional Health Services of Howard CountyCresco, IA · Critical Access Hospital · CCN 161328
Practice locations
Addresses where Mark E. Lassise is enrolled with Medicare (CMS data updated 2026-10-02).
- 250 S Crescent DrMason City, IA 50401
- 308 N Maple Ave, Mercyone New Hampton Medical CenterNew Hampton, IA 50659 (641) 394‑4121
- 635 E US Hwy 9, Mercyone Forest City Family MedicineForest City, IA 50436 (641) 585‑2904
Group practices
Medicare enrollment lists Mark E. Lassise as a member of this group (CMS data updated 2026-10-02).
- North Iowa Mercy Clinics302 clinicians in the group
Specialties
- Psychiatryprimary
Other psychiatrists in Mason City
Clinicians with the same Medicare primary specialty in Mason City, IA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Colorado School Of Medicine, Denver |
| Graduation year | 1980 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1023002508 |
| 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