In 15 impotent patients, the effect of visual sexual stimulation was evaluated by measuring their urinary levels of adrenaline and noradrenaline, before and after stimulation. Both adrenaline and noradrenaline increased in the urine over the base levels in response to the visual sexual stimulation. The average increases were 1.5 times for adrenaline, and 1.4 times for noradrenaline. There was an evident correlation between the degree of sexual excitation and the excretion of adrenaline and noradrenaline into urine.