We searched for possible immunogenetic markers in steroid-responsive nephrotic syndrome of childhood (SRNS). The incidence of HLA-DRw7 was significantly greater in SRNS patients than in controls (71% in patients, 29.8% in controls, P < 0.005). The HLA-A and -B locus antigens occurred in normal frequencies. The relative risk factor for HLA-DRw7 in SRNS was 5.9. This report failed to show a relationship between HLA-DRw7 and atopy, use of alkylating agents or occurrence of relapse after remission induced by these agents. We believe that SRNS may be an immunologic disorder whose pathogenesis is related to an MHC-linked Ir gene.