We analyzed 17 cases of multicystic dysplastic kidney (MCDK) to document the natural history of MCDK and its management. One patient was nephrectomied for respiratory failure associated with MCDK. Follow-up studies of 14 kidneys revealed that 5 kidneys (36%) did not change in size, 7 kidneys (50%) decreased in size. Two kidneys (14%) increased in size during the follow up periods and were nephrectomized. Hypertension and malignancy was not observed in our cases. Evaluations for the contralateral kidney and urinary tract system were performed in 15 patients and 5 (33%) revealed abnormalities--two patients with VUR, 1 with PUJ stenosis, 1 with ureteral stricture and 1 with ectopic ureterocele. In our hospital, the management for MCDK is conservative in most cases. Nephrectomy is indicated when there are complications resulting from the size of MCDK, or when the kidney continues to increase in size after the second year of life.