BACKGROUND: A 54-year-old man with multiple myeloma underwent peripheral blood stem cell transplantation (PBSCT) with cells donated by his human leukocyte antigen (HLA)-identical sister. Eight months after PBSCT, the patient experienced chronic graft-versus-host disease with skin involvement (generalized erythema), mucosal ulceration, sicca syndrome, and elevated liver enzymes. Two years after PBSCT, the patient developed nephrotic syndrome with massive proteinuria, which required hospitalization. INVESTIGATIONS: Physical examination, blood and urine analyses, liver function tests, 24 h urinary albumin excretion and renal biopsy. DIAGNOSIS: Focal segmental glomerulosclerosis as a complication of graft-versus-host disease. MANAGEMENT: Prednisone, ciclosporin and an angiotensin-converting-enzyme inhibitor.