In an investigation of chronic fatigue in patients treated with radical or post-operative radiotherapy for carcinoma of the prostate, the Brief Fatigue Inventory, urinary and anorectal function questionnaires were completed by 103 patients 2.1 years (median) after treatment. The mean fatigue score (2.8+/-2.3) and the rate of severe fatigue (18.7%) were higher than published data for healthy controls (2.2+/-1.8 and 5%, respectively). Fatigue was significantly correlated with fecal incontinence and urinary symptoms, suggesting an association of chronic fatigue and late radiation toxicity in carcinoma of the prostate.