We have studied the effect of HLA-DRB1 alleles on the clinical presentation of 61 Kuwaiti Arab children with idiopathic nephrotic syndrome. DR7(*0701) was the most prevalent DR allele, found in 41/61 patients (67%) compared with 10/59 healthy controls (17%) (p<0.001). DR3(*0301-0308) allele was the second most common, found in 25% of patients compared with 26% of controls (not significant). There was no significant difference between DRB1*0701(DR7)-positive and DRB1*0701-negative patients in terms of steroid sensitivity, steroid dependency, or steroid resistance. Nevertheless, the former group had a significantly lower mean age of onset (35 months vs 53 months) and a shorter remission period following treatment with cyclophosphamide or chlorambucil (8 months vs 29 months). Our data highlight the role of the DRB 1*0701 allele in predisposing Kuwaiti Arab children with idiopathic nephrotic syndrome to a more prolonged course of the disease.