PIP: 146 HIV-1-positive pregnant women and 143 matched HIV-1-uninfected pregnant women participated in a study to assess the association of human herpes virus 8 (HHV8) and the development of Kaposi's sarcoma. 98 of the 189 evaluable infants born to the women were born to HIV-1-positive mothers; 26 of these 98 infants were infected with HIV-1. Maternal serum samples were available for all but 18. The sera were diluted and screened for antibodies to the HHV8 latency-associated nuclear antigens (LANA) expressed in the BCBL-1 cell line. Coded sera randomly included from 10 healthy blood donors were negative for anti-LANA, while sera from two patients with AIDS and Kaposi's sarcoma were positive. 12 of the 289 pregnant women were seropositive for anti-HHV8, a proportion consistent with other findings in high-risk non-pregnant women. HIV-1-infected Haitians have an increased risk of Kaposi's sarcoma. The present cohort included 91 women of Haitian origin, nine who were seropositive for anti-HHV8. The proportion of HHV8 seropositive women among Haitians is significantly higher than among other women. HHV8 seropositivity was not increased among women with HIV-1 infection and all 189 infants were seronegative for HHV8. These findings support the association between HHV8 infection and the risk of Kaposi's sarcoma.