The role of screening for early detection of Wilms' tumour (WT) in patients with aniridia (A), Beckwith-Weidemann syndrome (BWS) and hemihypertrophy (HH) has been explored. Of the 1,622 Wilms' tumour patients registered with the National Childhood Cancer Registry from 1971 to 1991, 41 were recorded as having A, BWS or HH. Twenty-eight of these had their anomaly diagnosed before the WT and 13 had screening procedures carried out, mainly abdominal ultrasound. In 8 patients the screening procedure detected the WT. There was no significant difference in stage distribution or outcome for any of the three subgroups who were not screened, screen-positive or screen-negative. We conclude that regular screening with abdominal ultrasound is not of proven value. Parents should be taught abdominal palpation and advised to seek appropriate advice for untoward symptoms.