One thousand individuals in the age group 18-69 were selected for a multistage nationwide random sample. Of the interviewees 68.3% were of the opinion that the risk of AIDS, in Portugal, is considerably high and 37.1% stated that they had feared being infected by the HIV; 28.0% established a connection between being afraid and the fact that AIDS is a serious/incurable disease; 31.5% believed that there are risks inherent to the health services; only 7.8% expressed fear of AIDS because of an infected partner. Only 42.6% regarded extra-marital sexual relations as either partially or totally acceptable. Sexual relations between youths were seen as totally acceptable by 11.9% and partially acceptable by 51.1%. Homosexual relations between men were seen as either totally or partially acceptable by 38%. Of the interviewees, 7.8% thought that recent treatments can definitely cure AIDS and 6.5% believed that with recent treatments HIV transmission would no longer be possible.