In a survey of 541 diabetic males, aged 20-59 years, 190 (35%) had erectile impotence. Using linear logistic regression models for analysis the five most significant associations with impotence were age (p < 0.001), treatment with either insulin or oral hypoglycaemic agents (p < 0.001), retinopathy (p < 0.001), symptomatic peripheral neuropathy (p < 0.001) and symptomatic autonomic neuropathy (p < 0.005). The greatest correlations were found in patients with severe microangiopathy, as demonstrated by proliferative retinopathy and symptomatic autonomic neuropathy. In addition the duration of diabetes and the presence of ischaemic heart disease, nephropathy and poor diabetic control may also be associated with diabetic impotence. It is concluded that diabetic impotence is still a common problem and may have a multifactorial aetiology.