Multicystic kidney was first described in a 7-month-old child. Some physicians advocate nephrectomy in such cases, while others have questioned this procedure. In 1986 the American Academy of Pediatrics, Section on Urology established the Multicystic Kidney Registry to identify and follow patients with multicystic kidney disease. To date 441 patients have been registered, of whom 260 were managed nonoperatively. Based on followup of these patients no kidneys were removed for hypertension, infection, pain or tumor development. Long-term findings show that multicystic kidney disease may take as long as 20 years to resolve, and followup testing will be necessary.