In this study we examined the characteristics of 60 subjects (49 M and 11 F, average age 32.3) out of 195 post-exposure pharmacological prophylaxis (PEP) to HIV, taken in our hospital from 2001 to 2008. The above-mentioned subjects are sexually exposed (or presumably exposed) to HIV. We considered both their sexual intercourse behaviour and protective measures, and sought to infer some trends in sexual behaviour in Italy. All the subjects were monitored until 180 days after exposure, as established by the national guidelines. Only one of the 60 people presented a seroconversion (he dropped out after a 15-day follow-up and after an inadequate 19-day prophylaxis). Another subject, a homosexual male, never previously tested, resulted positive at time 0 both for HIV-Ab and syphilis tests (due to previous risk-sexual exposure), which caused the suspension of the prophylaxis. No HBV, HCV or syphilis seroconversion occurred. Two other homosexual males showed a previously latent positivity to syphilis tests at time 0.