Several studies of Bowen's disease suggest that most lesions occur on the head and neck, a finding which does not concur with observations in clinical practice in the U.K. In order to test the hypothesis that this reported distribution is due to an increased tendency of physicians to submit lesions of Bowen's disease occurring at these sites for histopathological examination, in comparison with lesions at other body sites, 52 cases of Bowen's disease identified from out-patient clinic diagnostic records were compared with 56 cases derived from pathology records. In both groups, the majority of lesions were on the lower leg; a greater number in the clinical cases group (45/52; 87%) than in the pathology cases (26/56; 46%). The lower leg lesions were almost exclusively in women (96% of lower leg lesions occurred in women in each group). The pathology group contained more men (29%) than the clinical group (12%), and also more upper limb lesions (23% compared with 8% in the clinical group). There was no evidence that these differences were due to incorrect clinical diagnosis, and the likely explanation is that lesions diagnosed as Bowen's disease in men, or at sites other than the lower leg, are more likely to be biopsied than clinically typical lesions on the female lower leg. This type of bias is likely to affect larger series in which only biopsied cases are included, and may explain the discrepancy between observations reported in previous publications and the situation in routine clinical practice.