The authors found a 60% incidence of difficulties in sexual functioning in 57 male patients who had taken thioridazine. Ejaculatory problems were the most frequent dysfunction; a third of these patients experienced retrograde ejaculation. The incidence of sexual difficulties in 64 patients who had taken other major tranquilizers was only 25%. None of the latter group experienced retrograde ejaculation-most had difficulty achieving and maintaining erection. The authors recommend consideration of the possibility of sexual dysfunction in patients given thioridazine.