During a 15-year period 29 patients were treated for unilateral multicystic kidney. The diagnosis was obtained from antenatal ultrasonography in 17 cases, investigation of an abdominal mass at routine palpation in 10, UTI investigation in 1 and uraemia investigation in 1. Eleven patients had associated malformations. Further investigations included ultrasonography, intravenous pyelography, micturition uretrocystography and in a few cases computed tomography and Dimercapto-succinic acid (DMSA) scan. Percutaneous pyelography was performed in 9 cases. Twenty-six children were operated on and 3 were not operated, of which 1 with severe cardiac malformations, died. The age at operation was under 6 months in 14 cases and between 6 and 12 months in 8. Four children developed hypertension preoperatively but the hypertension disappeared within 1 week postoperatively in all cases. The indication for surgery in unilateral multicystic kidney seems to be clear if the patient is symptomatic. In the asymptomatic patient, the complications of a remaining multicystic kidney like hypertension, malignancy, infection and pain suggest a surgical approach at around 6 months of age.