Robert A. Zajac, MD
NPI 1013907963ActiveIndividual· Internal Medicine, Infectious Disease· San Antonio, TX
Internal Medicine, Infectious Disease (MD) in San Antonio, Texas, trained at Louisiana State University School of Medicine in New Orleans (class of 1981). Their prescriptions cost Medicare Part D more than their services did: $1,736,457 for 2,369 claims, against $265,002 paid for services in 2024. Abbvie Inc. was the largest of 7 companies reporting payments in 2025, $438.83 in all, mostly food and beverage.
Overview
| NPI | 1013907963 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | MD |
| Sole proprietor | No |
| NPI issued | Oct 24, 2005 |
| Last updated in NPPES | Aug 8, 2024 |
| Certified by provider | Aug 8, 2024 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Infectious Disease Primary | 207RI0200X | H3973 | TX |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Oct 9, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 4, 2026 | No match | — |
| New York OMIG · Nov 4, 2026 | No match | — |
| Ohio Medicaid · Nov 4, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 4, 2026 | No match | — |
| Washington HCA · Nov 4, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Infectious Disease (TX) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 450 |
|---|---|
| Services billed | 4,800 across 30 procedure codes |
| Paid by Medicare | $265,002 |
Part D prescriptions in 2024
| Prescriptions (claims) | 2,369 · 2,956 30-day fills |
|---|---|
| Patients | 462 |
| Total drug cost | $1,736,457 |
| Generic share | 81% of claims |
Education and affiliations
| Medical school | Louisiana State University School of Medicine in New Orleans |
|---|---|
| Graduation year | 1981 |
| Medicare specialty | Infectious Disease |
| Telehealth | Offers telehealth |
Medical group
- Robert A Zajac MD PASan Antonio, TX · 6 clinicians
Hospital affiliations
- Baptist Medical CenterSan Antonio, TX
- Connally Memorial Medical CenterFloresville, TX
- Medina Regional HospitalHondo, TX
- Methodist Hospital Stone OakSan Antonio, TX
- Peterson Regional Medical CenterKerrville, TX
Other facilities
- Accentcare Home Health of TexasHome health agency · San Antonio, TX
- Capitol Home HealthHome health agency · San Antonio, TX
- Crest Home HealthHome health agency · Boerne, TX
- Methodist Healthcare at HomeHome health agency · San Antonio, TX
- Texas Healthcare Solutions, Inc.Home health agency · San Antonio, TX
Industry payments (Open Payments)
- 2025$438.83 · 22 payments from 7 companies
- 2024$487.23 · 24 payments from 9 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Abbvie Inc. | $162.80 | 11 |
| Viiv Healthcare Company | $155.50 | 6 |
| Insmed, Inc. | $29.41 | 1 |
| Aimmune Therapeutics, Inc. | $26.05 | 1 |
| Paratek Pharmaceuticals, Inc. | $24.33 | 1 |
What the 2025 payments were for
- Food and Beverage$438.83 · 22 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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