Weiyun Z. Ai, MD
NPI 1649346842ActiveIndividual· Internal Medicine, Medical Oncology· San Francisco, CA
Internal Medicine, Medical Oncology (MD) in San Francisco, California, trained at Stanford University School of Medicine (class of 2000). Their prescriptions cost Medicare Part D more than their services did: $1,768,035 for 673 claims, against $66,609 paid for services in 2024. Abbvie Inc. was the largest of 4 companies reporting payments in 2025, $5,038 in all, mostly consulting fees.
Overview
| NPI | 1649346842 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | MD |
| Sole proprietor | No |
| NPI issued | Nov 28, 2006 |
| Last updated in NPPES | Jun 6, 2008 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Medical Oncology Primary | 207RX0202X | A78202 | CA |
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 - Medical Oncology (CA) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 222 |
|---|---|
| Services billed | 1,285 across 43 procedure codes |
| Paid by Medicare | $66,609 |
Part D prescriptions in 2024
| Prescriptions (claims) | 673 · 902 30-day fills |
|---|---|
| Patients | 104 |
| Total drug cost | $1,768,035 |
| Generic share | 81% of claims |
Education and affiliations
| Medical school | Stanford University School of Medicine |
|---|---|
| Graduation year | 2000 |
| Medicare specialty | Medical Oncology |
| Secondary specialties | Internal Medicine |
| Telehealth | Offers telehealth |
Medical groups
- University of California San FranciscoSan Francisco, CA · 1,839 clinicians
- UCSF Medical Group Business ServicesSan Francisco, CA · 1,598 clinicians
- Regents of the University of CaliforniaSan Francisco, CA · 732 clinicians
Hospital affiliations
- Marinhealth Medical CenterGreenbrae, CA
- UCSF Health St. Mary's HospitalSan Francisco, CA
- UCSF Medical CenterSan Francisco, CA
Industry payments (Open Payments)
- 2025$5,038 · 9 payments from 4 companies
- 2024$7,858 · 10 payments from 4 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Abbvie Inc. | $3,727 | 6 |
| Acrotech Biopharma Inc. | $1,125 | 1 |
| Adc Therapeutics America, Inc. | $103.95 | 1 |
| Pfizer Inc. | $82.23 | 1 |
What the 2025 payments were for
- Consulting Fee$4,569 · 2 payments
- Food and Beverage$469.43 · 7 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
Other Internal Medicine, Medical Oncology providers in San Francisco
- 1457385379
- 1326118043
- 1982740114
- 1356696215
- 1386619419
- 1679530018
- 1659637452
- 1326058777
- 1225529928
- 1457381014
- 1295792729
- 1942236997
All Internal Medicine, Medical Oncology providers in California →