A 9-year-old boy with hepatitis B-associated glomerulonephritis and nephrotic syndrome underwent antiviral combination therapy including interferon and acyclovir. Pretreatment evaluation showed that active hepatitis B virus replication with HBsAg, HBeAg, HBV-DNA and DNA-polymerase had occurred for a period of at least 4 years. Signs of liver disease were minimal; serum amino transferases were normal and liver histology showed chronic persistent hepatitis with positive HBcAg, HBeAg and HBsAg immunofluorescence. A kidney biopsy revealed membranous glomerulonephritis with deposition of HBcAg, HBeAg, IgG, C3, C1q and, on electron microscopy, virus-like particles. After 8 weeks of therapy, active viral replication ceased, HBe seroconversion occurred and the nephrotic syndrome disappeared. One year after treatment, the boy was asymptomatic. No viral markers could be detected in the kidney, but low-grade membranous glomerulonephritis persisted with deposition of C1q, IgG and C3, but not HBeAg, HBsAg or HBcAg. Liver histology showed a minimal aspecific portal infiltrate with weak membrane-bound HBsAg immunofluorescence; no HBcAg could be detected. For patients with active viral replication and deposition of HBc, HBe immune complexes in the kidney, antiviral therapy can be beneficial, even in the absence of active liver disease.