We report here an adult case of IgA nephropathy associated with episodes of recurrent tonsillitis. Various kinds of viral antigens were examined in the renal and tonsillar tissues by immunofluorescence. Granular depositions of adeno- and herpes simplex viral antigens were detected in the glomerular mesangial areas and in the tonsillar epithelial cells by immunofluorescence. IgA and IgAl deposits were also observed in the glomerular mesangial areas. It was suggested that IgA nephropathy might be caused by multiple antigenic substances, including adeno- and/or herpes simplex viruses, located in the tonsillar regions.