Nutcracker syndrome(renal vein entrapment syndrome) is probably more common than previously suspected. The nutcracker phenomenon refers to compression of left renal vein between aorta and superior mesenteric artery that results in elevation of pressure in left renal vein and develoment of collateral veins. This syndrome occurs in relatively young and previously healthy patients and is characterized by intermittent gross hematuria due to left renal vein hypertension, at times associated with flank pain, abdominal pain or varicocele. We report a 17 years-old male patient with this syndrome presented with flank pain, abdominal pain, and intermittent gross hematuria for 3 months. Urinalysis revealed protein(-), blood(+++), many RBC with only 1% of dysmorphic RBC. IVP and cystoscopy showed no remarkable finding but doppler ultrasonography and abdominal spiral CT revealed compression of left renal vein between aorta and superior mesenteric artery. Renal venography showed compression of left renal vein and collateral circulation to left gonadal vein and the pressure gradient between left renal vein and inferior vena cava was 11mmHg. The nutcracker syndrome should be considered as one of the causes of nonglomerular hematuria. All patients with unexplained severe left flank or abdominal pain, or unilateral hematuria from the left on cystoscopy, should be studied by selective renal venography and pressure measurement in inferior vena cava and renal veins. The patient with this typical syndrome could be treated surgically, by transposition of left renal vein and resection of collateral veins as the procedure of choice to correct the underlying pathologic process and eliminate these troublesome symptoms.