Ethnicity and age play important roles in the epidemiology of idiopathic nephrotic syndrome (INS) in children. The purposes of this study were to compare the clinical features, renal histopathology, steroid response, and long-term prognosis in Chinese children between different age groups. This is a retrospective cohort study of children aged between 2 and 18 years old with INS. Patients were divided into two groups according to age. Group I consisted of children between 2 and 8 years old (n=49). Group II consisted of the remaining patients (n=50). The clinical biochemical parameters, response to steroid treatment, renal histology, and long-term outcomes were analyzed. The biochemical parameters at the onset were similar in the two groups. Group II had a significantly higher frequency of microscopic hematuria (P=0.011). Of the 67 children biopsied, minimal change disease was the most common histopathology for both groups. There was a higher frequency with focal and segmental glomerulosclerosis in group II (24% vs. 6.1%), but the difference between the two groups was not significant. During follow-up, the frequency of hypertension was significantly higher in group II (P=0.006). Two cases in group I developed chronic kidney disease (CKD) vs. eight cases in group II. The frequency of progression to CKD is significantly higher (P=0.042) in Group II. In conclusion, children beyond 8 years of age with INS have a higher incidence of microscopic hematuria, higher risk of hypertension and progression to CKD in long-term follow-up.