Purpose : Nutcracker syndrome refers to compression of the left renal vein(LRV) between the aorta and superior mesenteric artery(SMA) that results in elevation of pressure in the LRV and development of collateral veins. It must be considered as a possible factor when hematuria or proteinuria occurs in a healthy child. The purpose of this study is to determine the time to spontaneous resolution in childhood nutcracker syndrome, and to observe whether this is affected by sex, age, proteinuria or initial ratio of peak velocity of LRV. Methods : We investigated 26 patients who were found to have spontaneous resolution by follow-up Doppler ultrasonography among 117 patients diagnosed with nutcracker syndrome by renal Doppler ultrasonography from May 2001 to December 2005. We determined the time to spontaneous resolution in childhood nutcracker syndrome, and observed whether the duration was affected by sex, age, proteinuria or initial ratio of peak velocity. Results : 26 patients(59%) achieved spontaneous resolution by 1.2 years(mean). The time to spontaneous resolution of childhood nutcracker syndrome in 26 patients was $16.71{pm}9.99$ months(range 6.0-49.2). The time to spontaneous resolution was not affected by sex, age, proteinuria nor initial ratio of peak velocity of LRV. Conclusion : More than half of the patients who were diagnosed by renal Doppler ultrasonography achieved spontaneous resolution. The time to spontaneous resolution was not affected by sex, age, proteinuria nor initial ratio of peak velocity of LRV.