In summary, IgA-associated glomerulonephritis is an interesting clinical problem. The immunohistochemical identification of renal IgA deposits is the sine qua non of its diagnosis, although most of the patients reported have had hematuric syndromes, particularly recurrent gross hematuria. The importance of this immunopathologic entity devolves from the crucial use of special stains to identify IgA, the enigmatic role of IgA, the usual mesangioapthic expression of histologic response, and the ill-defined relationship of this clinical problem to nephropathies associated with systemic diseases that also have glomerular IgA deposits. Although still unproven, it is likely that the usual instance of IgA-associated glomerulonephritis is due to deposition of circulating immune complexes containing IgA. The nature of the exciting antigen(s), quantitative measures and characteristics of such complexes, and the role of mediating systems, including coagulation, have not yet been elucidated.