OBJECTIVES:To discover what factors affect lay people's judgments of the acceptability of physician assisted suicide and euthanasia and how these factors interact. DESIGN:Participants rated the acceptability of either physician assisted suicide or euthanasia for 72 patient vignettes with a five factor design--that is, all combinations of patient's age (three levels); curability of illness (two levels); degree of suffering (two levels); patient's mental status (two levels), and extent of patient's requests for the procedure (three levels). PARTICIPANTS:Convenience sample of 66 young adults, 62 middle aged adults, and 66 older adults living in western France. MAIN MEASUREMENTS:In accordance with the functional theory of cognition of N H Anderson, main effects, and interactions among patient factors and participants' characteristics were investigated by means of both graphs and ANOVA. RESULTS:Patient requests were the most potent determinant of acceptability. Euthanasia was generally less acceptable than physician assisted suicide, but this difference disappeared when requests were repetitive. As their own age increased, participants placed more weight on patient age as a criterion of acceptability. CONCLUSIONS:People's judgments concur with legislation to require a repetition of patients' requests for a life ending act. Younger people, who frequently are decision makers for elderly relatives, place less emphasis on patient's age itself than do older people.