Purpose: The purpose of this paper is to train primary health care workers to be trainers and implementers of community-based AIDS prevention activities in Oyo State, Nigeria, by describing an evaluation of the project. Design/methodology/approach: A total of 148 primary health care workers recruited from the 33 local government areas (LGA) of the state were trained as trainers. They were provided seed grants to replicate similar training for health workers, implement and evaluate community-based AIDS prevention activities. Questionnaires were used before and after the training and the community based projects to evaluate its impact on knowledge of cause of AIDS, routes of HIV transmission, signs and symptoms of AIDS, and precautions to prevent. Findings: At pre-test, only 30.8 percent of trainers could list at least four signs and symptoms of AIDS compared with 70.9 percent who could do so after the training. The trainers trained 973 health workers; the number trained ranged from 20-80 with a mean of 32.4. The trainers also implemented community-based AIDS prevention interventions which reached 2,082 persons including adolescents (48.2 percent), long-distance drivers (16.6 percent), market men and women (15.8 percent), female sex workers (14.2 percent), traditional birth attendants (4.6 percent) and herdsmen and women (5.6 percent). The evaluation conducted after four months of implementation of the community-based projects showed improvement in knowledge of HIV among all the target groups. It suggests reduction in reported unprotected sex among drivers (from 44 percent at pre-test to 18.9 percent at post-test) and increase in reported consistent use of condoms (from 53.4 percent at pre-test to 71.4 percent at post-test) among female sex workers. Research limitations/implications: Primary health care workers can successfully implement community-based HIV/AIDS prevention activities. Practical implications: Primary health care workers can make important contributions to HIV/AIDS prevention and control efforts. Originality/value: Health education interventions delivered by primary health care workers multiplied the effects of HIV/AIDS prevention and control activities. (Contains 4 tables.)