The report deals with the results of experimental studies in rats confirming the report made by Michael concerning an occurrence of impotence in male patients following electroconvulsive shock therapy. 1) Successive e lectroconvulsive shock to male adult rats resulted the most remarkable change in the zona fasciculata of the adrenal cortex, of which function showed very com plicated changes either hyper- or hypo-functional status. 2) Daily electroconvulsive shock given to male adult rats once a day resulted extinction of fertilizing ability in 5 weeks, which recovered after cessation of the electroconvulsive shock. Based on an absence of abnormality in sexual behavior and spermatogenic finding, the extinction of fertilizing ability is supposed to be due to disturbances of erection and ejaculation mechanisms. Namely 3 kinds of conditions, i) disturbance of erection mechanism with normal ejaculation, ii) disturbance of ejaculation mechanism with normal erection and iii) disturbances of both erection and ejaculation mechanisms are supposed following the electroconvulsive shock. 3) As the cause of disturbanc e of erection and ejaculation, the histological findings and reported results suggest us a decrease in sensitivity of seminal vesicle, prostate gland and penis to stimuli derived from decreased production of androgen and a decrease in response of nervous system concerning erection and ejaculation. In addition, a possibility of electroconvulsvie shock invasion to the higher center of erection and ejaculation is also considered. At any rate, the cause of the disturbances might be not a single one but a complicated mechanisms with the main factors being above two and addition of some other unknown factors.