A multicystic dysplastic kidney (MCDK) is one of the most frequent causes of abdominal mass in the neonate. Prenatal echography permits early and frequent diagnostics. It is a nonfamilial disease without associated cystic disease of the pancreas, liver or lungs. Indications for elective surgery are clear when there is a symptomatic disease. However, treatment of asymptomatic patients is controversial. A rising number of authors prefer nonsurgical approach, leaving MCDK intact with a close follow-up of patients for possible severe complications (malignancy, hypertension, infection, pain, rupture). We treated 15 patients with MCDK from 1984 to 1994. Diagnosis was passed antenatally in 7 (47%) patients, accidentally in 2, and based on the presence of abdominal mass in 6 patients. Two patients had renal failure due to the abnormal contralateral kidney. Nine patients were operated on and 6 were treated nonsurgically. The risk of complications associated with nonsurgical treatment, easiness of efficient surgery at the age of 3-6 months, avoiding stress in the child and family due to long-term follow-up, all suggest operative treatment. We suggest to parents both operative and nonoperative options, explaining the risk and danger of both. We believe that nephrectomy is the best solution in a child with MCDK who is growing, develops hypertension, with uncertain diagnosis or when adequate follow-up is impossible.