Data on patients with crescentic glomerulonephritis (> 50% glomeruli with crescents), referred to the Hospital for Sick Children during the past 13 years, were reviewed. Thirty patients (13 male, 17 female) aged 3.7-15.7 years (mean 9.5) were evaluated. Initial clinical features included: oedema (24/30), hypertension (19/30), gross haematuria (15/30), oliguria (15/30 )and a decreased glomerular filtration rate (GFR < 30 ml/min per 1.73 m2) (22/30). Henoch-Schonlein purpura was present in 9 patients, microscopic polyarteritis in 3, polyarteritis nodosa in 1, Wegener's granulomatosis in 1, systemic lupus erythematosus in 1, post-streptococcal glomerulonephritis in 2, mesangiocapillary glomerulonephritis in 7, anti-glomerular basement membrane glomerulonephritis in 2, and 4 were idiopathic. In 10 patients 50%-79% of glomeruli were affected by crescentic changes (group 1) and in the remaining 20, 80% or more (group 2). The crescents were cellular, fibrocellular or fibrous, and the degree of sclerosis was assessed. Patients in both groups were treated with plasma exchange, corticosteroids, anti-coagulants, cyclophosphamide and azathioprine in different combinations. On follow-up, 3 patients were dead, 1 was lost to follow-up, 12 were on dialysis/transplant programmes, 4 had a GFR of less than 30 and 10 a GFR of more than 30 ml/min per 1.73 m2. In our experience, 50% progressed to end-stage renal failure. The interval between disease onset and start of treatment was a prognostic factor for outcome. Fibrous crescents were associated with a worse outcome than fibrocellular crescents (P < 0.05). Outcome was not, however, related to the percentage of glomeruli affected (P > 0.05). Although the effectiveness of the individual components of the treatment regimens used was difficult to assess, one-third of patients at the latest follow-up had a GFR of more than 30 ml/min per 1.73 m2.