A 4-year-old boy developed nephrotic syndrome following varicella infection. Serologic studies during the early phase of the disease demonstrated a decrease in serum C3, C4, and properdin factor B. Renal biopsy revealed an acute proliferative glomerulonephritis with deposition of immunoglobulins A (IgA) and M, C3, Clq, and varicella virus antigen in the glomerulus, suggesting an immune complex deposition. Ultrastructurally, this suggested a postinfectious immune complex glomerulonephritis. These phenomena suggested that varicella virus antigen antibody complexes were deposited in the glomerulus and activated the classic and alternative pathway of complements, leading to an immune complex glomerulonephritis. During the nephrotic phase, an increase in OKT8 cells and decrease of the OKT4 cells were demonstrated. Two months later, this alteration returned to normal as the renal disease was in remission. This change of lymphocyte subsets during varicella infection may play a role in the pathogenesis of nephrotic syndrome.