Chronic paranasal sinusitis is one of the most prevalent diseases in the field of otolaryngology. Thirty histopathologic specimens from maxillary sinus were classified into infiltrating, edematous, fibrous or mixed type by morphologic findings of hematoxylin eosin staining, and then immunologically examined by peroxidase-antiperoxidase(PAP) method. This study was undertaken to evaluate the distribution of immunoglobulin-bearing cells in sinus mucosa, to compare the interrelation between the density of immunoglobulin(Ig.) and histopathologic type of the sinus mucosa, and to demonstrate the extracellular immunoglobulin. The following results were obtained. 1) In infiltration type, most of IgA-bearing cells were identified in stromal tissue. 2) In edematous type, IgA-bearing cells were identified in stromal tissue, and IgE and IgM-bearing cells were predominantly distributed in deep stromal tissue. IgA was predominantly identified extracellulary in stromal tissue. 3) In fibrous type, no IgE was identified. IgA-bearing cells were identified diffusely in all layers of sinus mucosa. 4) In mixed type, IgA-bearing cells were predominantly demonstrated in stromal tissue. 5) IgA-bearing cells were more predominantly located in stromal tissue of infiltrating type than that of edematous type. Extracellular IgA was more deeply stained in deep stromal tissue of edematous type than any other type. 6) IgA-bearing cells were predominantly located in stromal tissue of edematous type. Extracellular IgG was deeply stained in deep stromal tissue of edematous type. 7) IgM-bearing cells were predominantly observed in superficial stromal tissues. 8) IgE-bearing cells were predominantly observed in superficial stromal tissue of edematous type and whole stromal tissues of infiltrating type.