Orthostatic proteinuria has been recognized as a benign condition with a good prognosis and has not been associated with any underlying glomerular disease. The pathogenesis of orthostatic proteinuria is unclear. Recently, a few foreign reports suggested that the nutcracker phenomenon, which is known as a cause of asymptomatic hematuria, may also be a major cause of orthostatic proteinuria. We report a case of a 12-year-old female patient presenting only with orthostatic proteinuria, who was diagnosed as having nutcracker phenomenon by Doppler study and venography.