Quick answers
- Does Mary K. Ellis accept Medicare assignment?
- Yes. Medicare's clinician data says Mary K. Ellis accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Mary K. Ellis see?
- In 2024, CMS data shows 60 Original Medicare patients and 94 services for Mary K. Ellis. This counts Original Medicare only and measures volume, not quality.
- What is Mary K. Ellis's NPI number?
- 1134447329. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Mary K. Ellis, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 60 |
|---|---|
| Services billed to Medicare | 94 |
| Different services or procedures | 9 |
| Participating Medicare provider | Yes |
| Average age of these patients | 72 |
Most frequent services
- Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)45 services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)34 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High blood pressure75%
- High cholesterol75%
- Arthritis45%
- Ischemic heart disease37%
- Diabetes35%
- Anxiety28%
Hospitals where Mary K. Ellis works
Medicare's Facility Affiliation Data lists Mary K. Ellis at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Mount Sinai South NassauOceanside, NY · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 330198
Practice locations
Addresses where Mary K. Ellis is enrolled with Medicare (CMS data updated October 2, 2026).
- 196 Merrick RdOceanside, NY 11572 (516) 255‑8400
- 250 Fulton AveHempstead, NY 11550 (516) 485‑5710
Group practices
Medicare enrollment lists Mary K. Ellis as a member of this group (CMS data updated October 2, 2026).
- Mount Sinai School of Medicine148 clinicians in the group
Specialties
- Family Practiceprimary
Other family doctors in Oceanside
Clinicians with the same Medicare primary specialty in Oceanside, NY — not a recommendation.
Other clinicians in Mount Sinai School of Medicine
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 2009 (17 years since medical school) |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1134447329 |
| 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 October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- 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