Transmission of HIV in many Caribbean countries has followed the pattern of initial predominance among homosexual and bisexual males, with the infection subsequently spreading into the heterosexual community. However, on Saint Lucia the epidemic began among heterosexual contacts of Saint Lucian laborers from Florida; in Bermuda 58% of AIDS cases have been in intravenous drug abusers; and in the Bahamas 59% of the AIDS patients have been heterosexuals and 19% children infected via the perinatal route. Seroprevalence of the human T-lymphotropic virus, type 1 (HTLV-I), whose modes of transmission resemble those of HIV, has been found to range from 2.3% in Trinidad and Tobago to 5.4% in Jamaica. In a study of HIV and HTLV-1 infection patterns in homosexual males in Trinidad and Tobago, the cohort was too small for confirmation that coinfection with these two viruses hastened progression in AIDS, but further investigation is warranted.