An epidemic of sexually transmitted diseases, culminating in the emergence of acquired immune-deficiency states, has developed among homosexually active men during the past ten to 15 years. This epidemic is reviewed in relation to causative factors, priorities for control, and recommendations for control and prevention. Causative factors are divided into physical, behavioral, cultural, and political factors. Given the complicated interactions of these factors and the numerous diseases epidemic in the homosexuality active population, priorities need to be established for research and control programs that take into account the overall health impact of each disease and the effectiveness of available and potential resources. Finally, educational programs must be developed that will overcome the limited effectiveness of public health control efforts in this area, or we may expect even more serious and widespread health care problems.