The clinical course of 66 boys and 49 girls with autosomal recessive polycystic kidney disease recruited from departments of paediatric nephrology was investigated over a mean observation period of 4.92 years. This is a selected study group of children from departments of paediatric nephrology who in most cases survived the neonatal period, since birth clinics did not participate. The median age at diagnosis was 29 days (prenatal to 14.5 years). We observed decreased glomerular filtration rates (GFRs) in 72% (median age at onset of decrease of GFR < 2 SD, 0.6 years; range, 0-18.7 years), and 11 patients developed end-stage renal disease. Hypertension requiring drug treatment was found in 70% (median age at start of medication, 0.5 years; range, 0-16.7 years). Kidney length was above the 97th centile in 68% of patients, and kidney length did not increase with age or deterioration of renal function. Urinary tract infections occurred in 30%, growth retardation in 25%, and clinical signs of hepatic fibrosis were detected in 46%. Thirteen patients (11%) died during the observation period, 10 of them in the first year of life. There was a statistically significant sex difference in terms of a more pronounced progression in girls. The survival probability at 1 year was 94% for male patients and 82% for female patients (p < 0.05) in this study. Urinary tract infections occurred more frequently in girls (p < 0.025) and were observed earlier. In addition, more girls had impaired renal function, developed end-stage renal disease and showed growth retardation; these differences, however, were not significant. For the children in this study, however, our results indicate that the long-term prognosis in the majority of cases is better throughout childhood and youth than often stated.