The amounts of IgA1- and/or IgA2-dominant immune complexes included in peripheral blood polymorphonuclear cells (PMN) were determined by the double immunofluorescence technique in patients with IgA nephropathy. The aim of the present study was to determine the prevalence of IgA1- and/or IgA2-dominant immune complexes phagocytized by PMN in patients with IgA nephropathy. 5 patients with IgA nephropathy and 10 healthy adults were examined. It was demonstrated that the percentages of IgA1 with C3 cytoplasmic inclusion bodies were significantly increased compared with those of IgA2 with C3 cytoplasmic inclusion bodies in patients with IgA nephropathy. It was suggested that IgAl -dominant immune complexes are phagocytized by peripheral blood PMN in patients with IgA nephropathy.