Attitudes towards AIDS prevention, AIDS-related knowledge, and sexual behaviour of Nigerian adolescents and their African-American counterparts in two geographic regions of the United States were compared to assess cross-cultural similarities and differences between the adolescents. This study was conducted as the first in a programmatic sequence of activities leading toward the adaptation of a risk reduction intervention that was developed in the US for implementation with Nigerian youths. Subjects (n = 511) completed self-report measures of AIDS-related knowledge, attitudes towards condoms, attitudes towards AIDS prevention, sexual behaviour over the past two months, self- and response efficacy, and perceived vulnerability. Between-group comparisons revealed that US adolescents were more knowledgeable, held more favourable attitudes towards prevention and toward condoms, reported more sex partners, engaged in higher frequencies of unprotected vaginal intercourse, and became sexually active at later age than Nigerian adolescents. The findings are discussed with respect to their implications for translating risk reduction interventions developed in the US for African-American adolescents for later cross-cultural implementation with adolescents in developing countries where such risk reduction efforts are urgently needed.