AbstractSolid‐phase enzyme immunoassays using recombinant gag and env proteins were developed to study humoral immune responses to HIV infection in a cohort of 105 hemophiliac patients. Thirteen patients with ARC or AIDS and 92 asymptomatic patients were studied. A cross‐sectional study showed a wide range of antibody responses to gag and env proteins; however, the differences between the ARC/AIDS and asymptomatic patients were statistically significant for both antigens (P1.5. These patient groups were followed for comparable periods of time (67.1‐71.7 mo). The asymptomatic patients with low gag antibody and the ARC/AIDS patients showed a similar pattern of antibody response to gag protein overtime. In hemophiliac patients with HIV‐1 infection a low titer of antibody to gag protein is not invariably associated with clinical deterioration and is not a useful serologic marker of impending progressio