The wide range of factors that may contribute to impotence is reviewed in an attempt to establish a systematized approach for assessing etiologic factors. The effects on potency of ageing, general fitness, weight, debilitating disease, use of therapeutic and other drugsincluding alcohol and neurogenic, vasculogenic, endocrine/metabolic, urogenital and psychogenic factors are considered and discussed. The review also affords a rationale for the methodology employed.