Detection of alpha 2-plasmin inhibitor (alpha 2-PI) and/or fibrinogen in glomeruli by immunofluorescence in 26 patients with IgA nephropathy was described. The present study showed that glomerular injuries such as glomerular adhesion to Bowman's capsule and the cellular and/or fibrous crescent were predominantly observed in glomeruli with alpha 2-PI and/or fibrinogen deposits in patients with IgA nephropathy. Alpha 2-PI coexisted with fibrinogen in glomeruli from patients with IgA nephropathy. It was postulated that the deposition of alpha 2-PI in vivo might lead to the accumulation of glomerular fibrinogen deposits in patients with IgA nephropathy. It was suggested that the depositions of alpha 2-PI and/or fibrinogen in glomeruli may be one of the exacerbative factors in glomeruli from patients with IgA nephropathy.