Different population groups in Papua New Guinea were examined for infestation with Trichomonas vaginalis. Melanesian women (44.6%) were more likely to be infected than Caucasian women (14.2%). Similarly, Melanesian men (10.9%) had a higher prevalence of infection than Caucasian men (0%). Among the women, infection with T. vaginalis was also correlated with increasing age, parity, and place of residence.