Hepatitis B virus (HBV) infection is recognised as an important cause of nephrotic syndrome in endemic areas. This paper retrospectively examines the natural history and treatment of 70 patients with membranous glomerulonephritis and 1 with mesangiocapillary glomerulonephritis associated with HBV infection. Thirty-seven patients were in complete remission by the end of the study. The average duration of proteinuria in these patients was 30 months. The cumulative probability of remission was 64% at 4 years and 84% at 10 years. Three patients were still nephrotic after more than 90 months of follow-up and 2 others had reached end-stage renal failure. Remission occurred within 6 months of clearing the antigen (HBeAg) in the majority of cases. Steroids alone were given to 10 patients and 2 received steroids and cyclophosphamide, with no beneficial effect. Three patients received interferon-alpha 2b. One cleared the HBeAg from the circulation and had a significant fall in proteinuria, but defaulted from follow-up a month after completing treatment. One had a reduction of proteinuria but remained HBeAg positive. There was no change in the condition of the third. Although the majority of children eventually enter remission, there is a significant morbidity associated with the disease. Steroids and other immunosuppressive therapy are of no benefit. Interferon therapy may be useful, but has not been adequately assessed.