The authors report on their experience about diagnosis and therapies concerning cases of impotentia erigendi on account of urological operations in the small pelvis in order to extirpate tumours (radical prostatectomy, total cystectomy). The oncological effectiveness of the nerve-sparing technique is pointed out. The therapeutic diagnostic level is shown for this type of iatrogenic impotence and the various therapeutic possibilities are pointed out in relation to the wishes of the patient and to his life expectancies.