Wilms' tumour, or nephroblastoma, is an embryonal cancer of the kidney that occurs mainly in young children. This is a very rare tumour among adults, with an incidence rate of less than 0.2 per million per year. The aims of this study were to report the survival of adults diagnosed with nephroblastoma in Europe and to analyse time trends and geographic variations in survival. All the adults (age range 15-99 years) diagnosed with a Wilms' tumour during 1983-1994 and registered by one of the 22 cancer registries in 16 countries contributing to the EUROCARE (European cancer registries study on cancer patients' survival and care) database were analysed. Relative survival at 1 and 5 years after diagnosis was estimated by age, sex, geographic area, period of diagnosis and tumour stage. A total of 143 patients, with a median age of 34 years, were included in the analysis. Crude annual incidence rates varied geographically between 0.17 and 0.27 per million. Overall relative survival was 69.9% (95% confidence interval (CI) 61.8-78.0%) at 1 year and 47.3% (38.2-56.4%) at 5 years. Survival was 2.1-fold higher for women than for men (95% CI 1.3-3.5). There was a non-significant trend for better survival for younger patients and localised tumours, but no improvement in survival by period of diagnosis. Survival was not different between geographic areas. Our results suggest a poorer outcome of nephroblastoma in adults compared with published results in children. This may, at least partly, be explained by the rarity of this diagnosis. Prognosis may be improved by the use of specific treatment guidelines for nephroblastoma in adults.