Since Claudius Galen of Roman anatomist demonstrated the paranasal sinuses of human body in Ca.130-Ca.120, a large body of knowledge on paranasal sinuses is available in the literatures. On looking over the literatures, no report was found as a statistical survey of paranasal sinusitis as this series in Korea. The author, therefore, reported the following series. The paper presents a statistical survey of 373 cases of paranasal sinusitis in Koreans, who were confirmed the disease either way of clinical and radiological aspects, at the Otolaryngological clinic of Severance Hospital, Yonsei University College of Medicine for past two years of 1963-1964 inclusively, and the results shows as follows. 1) Among 373 cases of paranasal sinusitis, the maxillary sinusitis is 303 cases(81.2 per cent), and the others were 24 cases(6.4 per cent) of maxilloethmoidal sinusitis, 10 cases(2.7 per cent) of maxillo-frontal sinusitis, and 36 cases(9.7 per cent) of pansinusitis. In the series, age distribution as peak incidence is between 15-19 aged groups(126 cases, 33.8 per cent), and the average age of the cases is 21 years in male and 24 years in female. The sex ratio between male and female is about 1.6 to 1. 2) Generally the most prominent symptoms of paranasal sinusitis are nasal stuffiness(49.8 per cent), hyperrhinorrhea(38.7 per cent), and dull frontal headache(50.0 per cent), and the others were frontal headache, anosmia and impairment of memory on order. 3) According to the duration of the disease since onset, the average shown 2 years and 11 months(2 years and 8 months in male, and 2 years 9 months in female), the median is 2 years below, and the mode is 1 year below to the duration. Also reviewed monthly distribution as peak incidence is in June(14.7 per cent), and seasonal distribution, in orderly incidence, shows as 31.3 per cent in summer, 26.5 per cent in winter, 26.4 per cent in spring and 15.8 per cent in autumn respectively. 4) Most frequent pathologic change of the nasal mucosa shows hypertrophy of the inferior turbin ate(58.1 per cent), and the polyp and polypoid change of turbinate(18.4 per cent) which are more frequent in complicated sinusitis than simple sinusitis cases, and more common incidences in bilateral or left side of the nasal cavity than right one. 5) Characteristically, the most common rhinorrhea is mucoprulent in nature (221 cases, 59.2 per cent), and this seems to be shifted to prulent rhinorrhea in more complicated state than simple sinusitis in fact. 6) And also the radiological picture of the paranasal sinusitis was classified into the ±, +, and ++ due on authors standards, the + group shows most common(175 cases, 46.9 per cent), and consquently the incidence of the ++ one shows more frequent in the complicated sinusitis. 7) There is about 9.1 per cent(34 cases) of diagnostic difference between clinical and radiological findings. Clinically, 11 cases were diagnosed as sinusitis, but no sinusitis was verified by means of radiological finding, and the remainder of 23 cases are counted as contrary way. 8) Among the whole 373 cases, 186 cases(49.9 per cent) had surgical treatment. Of them 111 cases(59.8 per cent) were received Caldwell-Luc’s operation, and the others were 51 cases(27.4 per cent) of Intra-nasal Antrostomy, and 24 cases(12.9 per cent) of Sinus Puncture and Irrigation.