Yohimbine is an alkaloid derived mainly from the bark of the African tree, Pausinystalia yohimbe. Although many pharmacological properties of yohimbine have been described, at the plasma concentration attained at recommended dosages in man the predominant activity is antagonism of alpha 2-adrenoceptors. For more than 70 years yohimbine has been used as a treatment for male and female sexual difficulties. It has enjoyed a reputation as an aphrodisiac although no effect on sexual drive in humans has been adequately demonstrated. Yohimbine has been evaluated in the management of erectile disorder by means of placebo-controlled but often poorly designed trials. It does appear to have a modest therapeutic benefit over placebo, particularly in essentially psychogenic erectile disorder, and is generally well tolerated. Yohimbine is not licensed in the UK.