Orthostatic proteinuria is documented as a benign condition and the most common cause of isolated proteinuria. The etiology and pathogenesis of orthostatic proteinuria is not clear yet. Recently there were a few report that nutcracker syndrome seemed to cause orthostatic proteinuria. We experienced a case of a twelve-yeat-old female patient with incidently discovered orthostatic proteinuria who was suspected to have nutcracker phenomenon by doppler sonography. We confirmed this patient as nutcracker syndrome by renal venography.