From 1962 to 1979, 74 men and one woman considered sexually abnormal have received surgical hypothalamotomies in the Federal Republic of Germany. This paper reviews the neurophysiological assumptions behind the surgery, the criteria for surgery, and the effects and side effects of surgery as far as has been documented by medical, psychiatric, psychological, sexual, and social data. The neurophysiological bases for hypothalamotomies on humans with deviant sexual behavior appear dubious, the indications make use of questionable scientific and clinical categories and assumptions, few reliable data have been submitted for side effects, and follow-up studies are based on poor methodology. Restrictive regulations against this type of "experimental therapy" are suggested.