In the last 10 years we have evaluated 63 patients with acute crescentic rapidly progressive glomerulonephritis (AC-RPGN), 46 of whom received pulse methylprednisolone (PM). The groups consisted of patients with no immune deposits, immune complexes, vasculitis, and antiglomerular basement membrane (anti-GBM) disease. Seventy-nine percent of non-anti-GBM patients improved versus 25% of unpulsed, p less than 0.005; 70% stopped dialysis (D) versus none of unpulsed, p less than 0.009; creatinine decreased from 8.6 before to 2.7 mg/dl after PM, p less than 0.05. Percent crescents and oligoanuria did not influence PM results, but did with conventional therapy (prednisone, cytotoxics, anticoagulants, supportive treatment). Seventeen percent of anti-GBM patients improved, none stopped D. In anti-GBM patients, serum creatinine less than 6 mg/dl was associated with a favorable response to PM, p = 0.045. Twenty-one percent of responding patients lost function at 19.8 months. The long-term response for non-anti-GBM patients was 62%. Patients with low chronicity on biopsy had shorter duration of disease (p = 0.006) and 92% initial, 85% long-term improvement; those with high chronicity had an immediate 71%, and 36% long-term response rate, p less than 0.02. Thus, PM is effective and appears superior to conventional therapy in treatment of non-anti-GBM AC-RPGN.