A case of unilateral multicystic dysplastic kidney in a 52-year-old woman is reported. Two abnormal round-like calcifications in left upper quadrant abdomen were found on upper gastrointestinal roentgengraphy for health screening. The computerized tomographic (CT) scan revealed a very small left kidney which was not enhanced and the ring and diffuse calcifications in it. It was not visualized by drip infusion pyelography. Left nephrectomy was performed. The kidney, which was very small, had two cysts the walls of which were calcified. The left ureter and renal vessels were absent. Histological appearance shows typical multicystic dysplastic kidney (MCDK). Literature is reviewed. However, the therapy for MCDK is still controversial.