To investigate whether age at onset of steroid-sensitive nephrotic syndrome (SSNS) is predictive of subsequent relapses, or influences outcome, we retrospectively studied 60 patients who were under 10 years of age at onset and were followed for over 10 years. They were divided into three groups according to age at diagnosis: group 1-3 (1.0-3.9 years at onset, n=24), group 4-6 (4.0-6.9 years at onset, n=22), and group 7-9 (7.0-9.9 years at onset, n=14). In the 51 patients with long-term remission, defined as remaining relapse-free over 3 years, the total number of relapses was significantly more in group 1-3 (n=18) than in group 4-6 (n=19), and the interval between onset and long-term remission was significantly longer. Group 4-6 and group 7-9 had fewer patients with active disease at 10 years, follow-up than group 1-3, as assessed by the Kaplan-Meier method. These data suggest that the age at onset of SSNS influences the clinical course (i.e., frequency of relapses) and the time to reach long-term remission. An age of less than 4 years at onset of SSNS is associated with greater likelihood for frequent relapses and a greater time interval to attain long-term remission.