We have reviewed all paediatric kidney tumours seen in the West Midlands Health Authority Region over a 30-year period. There were 205 cases confirmed after a review of the pathology by three paediatric pathologists. Seven were cases of bone metastasising renal tumour (clear cell sarcoma), 5 were rhabdoid tumours, 2 were renal cell carcinomas, and 13 were mesoblastic nephromas. In 3 cases, it was not possible to define further the histological diagnosis. The remaining 175 cases were considered to be Wilms' tumour (86%), which is equivalent to an incidence of 5.7/10(6)/year. In the cases of Wilms' tumour, there were 91 boys and 84 girls (1.1:1). The majority of patients were Caucasian with only 7% of non-Caucasian origin. At presentation, 78% of the patients were less than 5 years old. All of these patients except 9 had surgery as part of their treatment, 154 children had total nephrectomy, 3 had partial nephrectomy, and 9 had other surgical procedures. The majority also received chemotherapy and radiotherapy. Sex, chemotherapy, and stage all had prognostic significance in univariate analysis. The actuarial survival at 10 years increased from 17% for patients treated in the first decade of the study to 78% for patients treated in the third. DNA characteristics were investigated using flow cytometry in paraffin-embedded material and adequate information was obtained in 73 cases of Wilms' tumour. Only 7 had aneuploid tumours. Univariate survival analysis of these 73 results showed that stage, sex, the percentage of cells in the synthetic phase and the proliferative index from the DNA investigations had predictive value.