Background: Although most children with idiopathic nephrotic syndrome will respond to corticosteroid therapy, 80-90 % suffer one or more relapses. Methods: Using Cox proportional hazard models, we analyzed predictors of remission and relapse in 1-year follow-up data on children aged below 15 years with new-onset nephrotic syndrome. Results: Of 129 children, 107 achieved remission with corticosteroid therapy and 86 subsequently relapsed. Boys achieved remission more often than girls (adjusted hazard ratio [AHR] 1.52, 95 % confidence interval (CI) 1.02-2.3). Boys relapsed significantly more frequently than girls (AHR 1.77, 95 % CI 1.11-2.83) and were more likely to have frequently relapsing disease (AHR 3.3, 95 % CI 1.18-9.23). The risk of first relapse increased with the number of days to first remission (AHR 1.02, 95 % CI 1.01-1.04). The risk for a frequently relapsing course increased with a shorter time from remission to first relapse (AHR 0.92, 95 % CI 0.87-0.97). Conclusions: In idiopathic nephrotic syndrome, boys are more likely to respond initially, more likely to relapse, and to be classified as having frequently relapsing nephrotic syndrome. A decrease in time from remission to first relapse predicts for a frequently relapsing course.