To provide further evidence for the heterosexual transmission of the acquired immunodeficiency syndrome (AIDS) in Greece we examined 53 Greek female steady heterosexual partners of 53 anti-HIV-positive men. Human immunodeficiency virus (HIV) transmission was estimated by the detection of anti-HIV antibodies. Our results showed that 27.8% (5 of 18) of the female partners of bisexuals, 33.3% (2 of 6) of intravenous drug abusers (IVDA), and 100% (4 of 4) of those who had lived for a long time in Africa were found anti-HIV positive. In contrast, only 4% (1 of 25) of the studied sexual partners of hemophiliac carriers were found to be HIV seropositive. The use of condoms seemed to be the most important factor in reducing HIV transmission. According to our results the duration of sexual relationships and the practice of anal intercourse did not increase the possibility of seroconversion. These results confirm the heterosexual transmission of HIV. However, further studies should be conducted to evaluate the relative role of various risk factors and the overall importance of heterosexual spread of HIV infections.