The objective of this study was to evaluate the features and calculate the frequency of sex-reassigned subjects who had applied for reversal to their biological sex, and to compare these with non-regretful subjects. An inception cohort was retrospectively identified consisting of all subjects with gender identity disorder who were approved for sex reassignment in Sweden during the period 1972-1992. The period of time that elapsed between the application and this evaluation ranged from 4 to 24 years. The total cohort consisted of 218 subjects. The results showed that 3.8% of the patients who were sex reassigned during 1972-1992 regretted the measures taken. The cohort was subdivided according to the presence or absence of regret of sex reassignment, and the two groups were compared. The results of logistic regression analysis indicated that two factors predicted regret of sex reassignment, namely lack of support from the patient's family, and the patient belonging to the non-core group of transsexuals. In conclusion, the results show that the outcome of sex reassignment has improved over the years. However, the identified risk factors indicate the need for substantial efforts to support the families and close friends of candidates for sex reassignment.