A case of nontraumatic subcapsular renal hematoma was reported. The patient was a 41-year-old woman. She complained of right flank colic pain. Her excretory pyelography showed right hydronephrosis and ureteral stone, and demonstrated a large mass involving the right kidney and medial displacement of its collecting system. Ultrasonic examination and computed tomography revealed right subcapsular renal hematoma. Since we found no malignancy, we made a puncture and drained the lesion. A bloody aliquot was gained and its cytological examination was negative. Her clinical course was uneventful. After 6 months the hematoma was absorbed clearly. A review was made of 38 cases of nontraumatic subcapsular renal hematoma, including our own case. Of these, the cause was unidentified in 17 cases. Hydronephrosis, mostly associated with calculi, renal infarcts, nephritis and renal cell carcinoma followed. Of 38 cases, 2 (5.3%) were of malignant tumor.