An Immunohistopathological study has been performed for 1543 cases of the chronic paranasal sinusitis(male 826 cases, female 717 cases), which were obtained from 1973 to 1986 at the Kyung Hee University Hospital using DAKO PAP Kit. They were correlated with histopathological findings, age and site distributions. The results are as follows : 1) The histopathological classification were edematous type, infiltrative type, fibrosing type and mixed type. 2) The male & female ratio was 1.2 : 1. 3) The age distributions of the male patients were 0-9 years 1.7%, 10-19 years 34.6%, 20-29 years 26.5%, 30-39 years 17.3%, 40-49 years 10.5%, 50-59 years 6%, 60-69 years 2.7%, and 70-79 years 0.5% and those of the female patients were 0-9 years 0.4%, 10-19 years 25.2%, 20-29 years 41%, 30-39 years 13.8%, 40-49 years 9.8%, 50-59 years 5.7%, 60-69 years 3.6% and 70-79 years 0.4%. 4) The site distributions were maxillary sinus 97.7%, ethmoid sinus 6.2%, frontal sinus 0.2%. 5) The histopathological types and the incidence of the male patients were 33.3%, 30.8%, 24.7%, 11.3% in fibrosing type, edematous type, mixed type, infiltrative type respectively and those of the female patients were 31.2%, 29.1%, 26.6%, 13.0% in fibrosing type, edematous type, mixed type, infiltrative type respectively. 6) The immunohistologic findings revealed numerous IgG, IgA and less frequent IgM producing cells in the infiltrative type and the allergic type. The fibrosing type and the simple edematous type showed rare immunoglobulin producing cells. In conclusion, a certain immunologic role is suspected as an important pathogenesis of the chronic paranasal sinusitis, especially the infiltrative type.