To analyze the characteristics of persons seeking HIV testing, and to evaluate the potential effectiveness of a regional program of confidential counselling and testing for HIV infection, we reviewed data on 5127 clients seen from July 1985 to December 1990 in a major counselling and testing site of the city of Rome. During the study period, the number of clients attending the service increased without a parallel rise of the number of newly identified HIV seropositive subjects. Consequently, the seroprevalence rate decreased from 27.6% in the second half of 1985, to 4.3% in the second half of 1990 (p < 0.001). This decrease appears to be associated with the increasing attendance of low risk subjects and of those referred for testing by family practitioner. The study suggests the need for more efficient strategies to reach persons at higher risk for HIV infection.