Localized cystic disease of the kidney is a rare entity with the gross and microscopic features of autosomal dominant polycystic kidney disease localized to only a portion of a kidney, and negative family history. We report a case of localized cystic disease of the kidney in a 38-year-old woman who complained of intermittent right flank pain for 1 year. The resected kidney showed multiple cysts measuring up to 4.0 3.5 3.0 cm, which were scattered throughout the mid- and lower poles of the kidney. Microscopically, the cystic lesion was composed of numerous cysts of variable size, lined by flattened epithelium. The intervening septa of the cysts contained normal or compressed renal tubules and glomeruli. Neither dysgenetic tissue such as immature cartilage or primitive mesenchymal tissue nor malignant cells was identified. Localized cystic disease should be included in the differential diagnosis of cystic lesions in the kidney.