The continuing escalation of the global HIV/AIDS epidemic has changed our perceptions of sexual health. This article reports on a study of nurses' and nursing students' perceptions of sexual risk behaviour in Finland, Estonia and Lithuania and of how these perceptions are associated with background variables. Questionnaire data were collected in year 2006 with a modified version of Chng and Moore's Safer Sex Scale (1993), which consists of 12 background questions and 10 items exploring nurses' and nursing students' perceptions of sexual risk behaviour. Responses were obtained from 1152 nurses and nursing students. Their perceptions of sexual risk behaviour appeared to be quite cautious. The results revealed statistically significant country differences, with Finnish and Estonian respondents showing more cautious perceptions of sexual risk behavior than Lithuanian respondents. Some background variables were found to be associated with perceptions of sexual risk behavior. Nurses' perceptions differed from those of nursing students: the latter were less cautious in their perceptions. The most important background factor was previous experience of nursing an HIV/AIDS patient: nurses and students who had such experience reported more cautious perceptions than those who did not. In addition, age was found to correlate with perceptions of sexual risk behavior. Nurses and nursing students need to be more aware of their own perceptions of sexual risk behavior and the impact of those perceptions on their clinical practice. Interventions need to be developed in order to promote safer sex practices. Health care personnel should have the opportunity in their training to work with HIV/AIDS patients.