Six factors were identified which might influence staff decisions: competence of patient to engage in the activity, degree of consent in sexual relationship, nature of sexual activity, location of sexual activity, sex of the initiating patient, and sex of the other patient. The sample consisted of 131 mental health professionals, including 69 men and 58 women, aged 25 to 79 years. After reading two of a series of narrative vignettes, the subjects completed a questionnaire assessing their perceptions about sexual activity among patients. The results showed that only location and form of sexual activity were significant. The findings indicated that mental health professionals need to examine their own prejudices, such as homophobia, and that institutional policies should focus on the importance of competence assessment in regard to decision making by psychiatric patients. 13 references