To study the local immune response to human immunodeficiency virus type 1 (HIV-1) in women infected by or exposed to HIV-1, 75 women were studied: 15 were IgG-seropositive but clinically asymptomatic, 15 had acquired immune deficiency syndrome (AIDS), 15 were IgG-seronegative with seropositive husbands, and 30 were healthy seronegative women who were selected as controls. Serum samples and vaginal secretions were tested for antibodies to HIV-1 IgG and IgA by Western blot analysis. Antibodies of the IgG and IgA classes were detected in serum samples and vaginal secretions from healthy seropositive women and from women with AIDS. Local IgG antibodies to all viral proteins were detected by Western blot tests. Genital IgA antibodies were mainly directed to the core proteins p18 and p25, the p68 reverse transcriptase, and the gp160 and gp41 glycoproteins; IgA antibodies to the glycoprotein gp120 were rarely recovered. Antibodies of both the IgG and IgA classes in genital secretions were directed to all viral proteins, including surface glycoproteins, and could play a role in limiting the virus infectivity on normal mucosa.