John M. Wallmark, M.D.
NPI 1689755365ActiveIndividual· Internal Medicine, Hematology & Oncology· Rockville, MD
Internal Medicine, Hematology & Oncology (M.D.) in Rockville, Maryland, trained at Hahnemann University College of Medicine (class of 1992). In 2024 Medicare paid $3,423,334 for 868 patients, and Part D covered 1,025 of their prescriptions, 68% of them generic. Novartis Pharmaceuticals Corporation was the largest of 26 companies reporting payments in 2025, $2,478 in all, mostly food and beverage.
Overview
| NPI | 1689755365 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | M.D. |
| Sole proprietor | No |
| NPI issued | Oct 18, 2006 |
| Last updated in NPPES | Aug 1, 2012 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Hematology & Oncology Primary | 207RH0003X | D0053177 | MD |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Nov 10, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 11, 2026 | No match | — |
| New York OMIG · Nov 11, 2026 | No match | — |
| Ohio Medicaid · Nov 11, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 11, 2026 | No match | — |
| Washington HCA · Nov 11, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Hematology/Oncology (DC); Practitioner - Hematology/Oncology (MD) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 868 |
|---|---|
| Services billed | 194,041 across 183 procedure codes |
| Paid by Medicare | $3,423,334 |
Part D prescriptions in 2024
| Prescriptions (claims) | 1,025 · 1,872 30-day fills |
|---|---|
| Patients | 206 |
| Total drug cost | $4,711,075 |
| Generic share | 68% of claims |
Education and affiliations
| Medical school | Hahnemann University College of Medicine |
|---|---|
| Graduation year | 1992 |
| Medicare specialty | Hematology/Oncology |
| Telehealth | Offers telehealth |
Medical group
- Maryland Oncology Hematology PAColumbia, MD · 104 clinicians
Hospital affiliations
- Adventist Healthcare Shady Grove Medical CenterRockville, MD
- Holy Cross Germantown HospitalGermantown, MD
- Sibley Memorial HospitalWashington, DC
- Suburban HospitalBethesda, MD
Other facilities
- Adventist Home Health Services, Inc.Home health agency · Silver Spring, MD
Industry payments (Open Payments)
- 2025$2,478 · 65 payments from 26 companies
- 2024$2,630 · 67 payments from 22 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Novartis Pharmaceuticals Corporation | $1,241 | 21 |
| Pfizer Inc. | $126.20 | 5 |
| Array Biopharma Inc | $97.94 | 3 |
| Tempus Ai, Inc | $92.18 | 1 |
| Abbvie Inc. | $90.14 | 3 |
What the 2025 payments were for
- Food and Beverage$1,478 · 53 payments
- Long term medical supply or device loan$999.96 · 12 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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All 27 hematologist-oncologists in Rockville · All hematologist-oncologists in Maryland