Work conducted in the mid-1980s suggested that dentists in the Republic of Ireland felt uncomfortable about treating patients who were HIV-seropositive. It seemed that with greater understanding of the behaviour of the virus, dentists' attitudes would be modified accordingly. The aim of this study was to assess the reactions of Irish dentists to the treatment of HIV-positive patients. All dentists currently on the register were sent a questionnaire to assess their knowledge, attitudes and clinical behaviours. Over 60% of dentists responded. The study highlights dentists' responses to HIV infection suggesting that they are fearful of the virus. They perceive HIV as dangerous to themselves, their other patients and their practice. The findings indicate that attitudes relating to dangerousness remain a significant obstacle in the treatment of this patient group.