A Japanese boy aged 14 years presented with gross hematuria associated with mild proteinuria and was diagnosed as having nutcracker syndrome. Magnetic resonance angiography (MRA) revealed significant compression of the left renal vein between the aorta and the superior mesenteric artery with collaterals. A percutaneous renal biopsy on the right kidney revealed no evidence of glomerular or interstitial changes with immune deposition. He was observed closely without any intervention thereafter. Although repeat MRA performed 4 years after our first observation disclosed the development of collateral veins, severe hematuria with an intermittent exacerbation remained unchanged. During the next 2 years, the hematuria completely subsided spontaneously. Although the etiology of spontaneous remission of the disease remains speculative, his good physical development (i.e., approximately 10 cm taller than his height at the onset) may change presumptive hemodynamic factors. These clinical observations suggest that a proportion of pubertal patients with nutcracker syndrome should be treated conservatively for a relatively long time.