The objective of the study was to evaluate the effect of a reference programme and a mass media campaign about prevention of HIV. A "before-after" study including three measurements was carried out. Before, immediately after, and six months after the intervention the GPs completed questionnaires, and prospectively registered consultations involving the prevention of HIV. Immediately after the intervention the median number of consultations dealing with HIV was significantly higher (three as compared to two during ten working days). The rise in activity was due to a higher number of consultations initiated by the patients. The conclusion was that the reference programme did not cause a significant change in the GPs' behaviour. However, the mass media campaign resulted in a temporary increase in the number of patients who took the initiative to talk about HIV with their GPs.