To clarify the therapeutic role of plasmapheresis (PP) for patients with Henoch-Schönlein purpura (HSP) nephritis, the clinical courses of nine children with a rapidly progressive type of HSP nephritis, who were treated with PP as the sole therapy, were retrospectively evaluated. All patients had nephrotic-range proteinuria (4.9 +/- 2.5 g/m2/d, mean +/- SD) and decreased glomerular filtration rate (GFR) (46.5 +/- 9.5 mL/min/1.73 m2) at the time of the initiation of PP. Biopsy specimens taken before PP showed large crescents involving more than 50% of the glomerular circumference in 56.8 +/- 6.9% of the glomeruli examined. The mean interval between disease onset and initiation of PP was 39.1 +/- 22.1 days. The PP regimen consisted of thrice-weekly treatment for 2 weeks, then weekly treatment for 6 weeks. No patients received any steroids or cytotoxic drugs, except for the use of steroids to manage severe abdominal pain. All patients responded promptly to PP with improvement in renal function, reduction of proteinuria, and subsidence of purpuric rash and abdominal pain. Six of nine patients showed further improvements without any other treatments; four had complete recovery, and two had only microscopic hematuria at the latest observation (follow-up period, 9.6 +/- 4.3 years). The remaining three patients showed a rebound increase of proteinuria after completion of PP; two of whom progressed to end-stage renal failure at 14.1 years and 1.8 years after disease onset. Because all patients had the most severe forms of nephritis, reported to carry a grave prognosis, this study suggests that PP as the sole therapy is effective in improving the prognosis of patients with rapidly progressive HSP nephritis, particularly if instituted early in the course of the disease. The role of PP in treating HSP nephritis deserves to be assessed further in larger randomized controlled trials.