Between June 1975 and March 1987, 662 renal biopsies were performed in 657 children at Seoul National University Children's Hospital. Nephrotic syndrome was the most indication for renal biopsy and accounted for 62% of all cases. Of these, 57% showed minimal change lesions and 21% showed focal segmental glomerular sclerosis. Nephropathy, associated with Australia-antigen-positive hepatitis, was the most prominent cause of secondary nephrotic syndrome, and of these patients membranous nephropathy was found in 86%. Diffuse proliferative glomerulonephritis was found in 60% of patients with acute nephritic syndrome. Fifty-eight percent of children with haematuria were found to have either IgA nephropathy or Henoch-Schönlein nephritis. Fifteen children with acute renal failure were biopsied, 2 of whom had haemorrhagic fever.