['Recent reports have revealed that corticosteroid (PSL) therapy has a long-term beneficial effect for stabilization of renal function in progressive IgA nephropathy.', 'We analyzed serum creatinine (Cr), daily proteinuria and the results of other routine laboratory examinations during a short-term course of PSL therapy in 28 cases of progressive IgA nephropathy. The cases were divided into two groups according to changes in renal function during the PSL treatment period: group I (15 cases), improved renal function; group II (13 cases), no significant change in renal function.', 'In group I, serum Cr and proteinuria were significantly decreased, with maximum effects observed at 3 months of PSL therapy, and remained low during the period of treatment. In contrast, group II showed no significant changes in serum Cr levels during the period of therapy, although proteinuria was transiently decreased after 3 months of therapy. Histologically, cellular/fibrocellular (C/F) crescents and/or segmental glomerular necrosis (SGN) occurred with a significantly higher incidence in group I (87%) than in group II (46%) (p < 0.05).'] Are cellular crescents and segmental glomerular necrosis in IgA nephropathy indicative of the beneficial effects of corticosteroid therapy?