Renal cell carcinoma presented as a traumatic ruptured kidney is rare. A 22-yr-old female patient was referred to our emergency room on account of blunt abdominal trauma with hypo-volemic shock. The computerized tomography of the abdomen revealed a suspected cortical lac-eration over the upper pole and a lower-density tumor mass at the lower pole of the left kidney. Emergency laparotomy was performed due to persistent shock state. The operative findings dis-closed a ruptured tumor and no cortical laceration over the normal cortex of the left kidney. The pathology confirmed the diagnosis of renal cell carcinoma. We suggest that any exploration of suspected abdominal injury should use care in palpation of both kidneys, especially when facing the negative abdominal condition. (J urol R.O.C., 9:162-165,1998)