Background: Henoch-Schönlein Purpura (HSP) is a common childhood vasculitis with manifestations in numerous organ systems, including glomerulonephritis. Patients with more severe HSP-associated glomerulonephritis may develop chronic renal failure. Currently, no widely accepted treatment protocols exist for patients with significant renal involvement. Methods: We retrospectively reviewed the clinical courses of 12 children (mean age 9 years) with HSP glomerulonephritis treated with high-dose corticosteroids plus oral cyclophosphamide. All patients had nephrotic-range proteinuria, and all had significant histopathologic changes on biopsy, including crescentic nephritis in 10 patients. Treatment consisted of either intravenous pulse methylprednisolone or oral prednisone followed by oral cyclophosphamide (2 mg/kg/day) for 12 weeks, along with either daily or alternate-day oral prednisone. Prednisone was tapered following completion of cyclophsophamide. Results: Serum albumin rose significantly after treatment from 2.8 ± (SD) 0.5 to 3.7 ± 0.4 g/dl (p < 0.001), and there was a concurrent reduction in proteinuria, as reflected by decreasing serial protein-to-creatinine ratios: from 6.3 ± 4.4 to 0.8 ± 0.8 (p = 0.002). Renal function remained normal in all patients. Hypertension developed during treatment in 10 patients, all but 1 of whom were normotensive at last follow-up, 35 ± 17 months following biopsy. Conclusions: We conclude that treatment of children with HSP nephritis with high-dose corticosteroids plus oral cyclophosphamide is safe and, as in nephrotic syndrome, appears to significantly reduce proteinuria which is a known risk factor for the development of renal insufficiency in HSP. Further studies with larger numbers of patients should be conducted to confirm this finding.