We found that the incidence of FVIII inhibitors was low among HIV-positive patients with severe hemophilia A. A British study also found a low incidence of inhibitors (4.1%) among HIV-positive patients with severe hemophilia, compared with a 3-fold higher incidence among HIV-negative patients (P < 0.001), which may be related to the immune status of HIV-positive patients. The gene discussed is F8; the disease is hemophilia.