In Otolaryngology, X-Rays are of great importance in the diagnosis and evaluation of maxillary sinus disease, especially the sinusitis. In addition to the radiographic findings, we can take the transillumination method which is a cheaper and simpler way than the roentgen examination for maxillary sinusitis. The purpose of this study was to make a comparison between roentgen examination and transillumination of the chronic maxillary sinusitis. The results were as following ; 1) Sex distributions were male : female ; 1 : 1.1 2) Age distributions were 42 cases in the 1st decade, 40 cases in the 2nd decade. 3) Duration of disease was from 1yr to 3yrs in 37 cases and from 3yrs to 6yrs in 22 cases. 4) Incidence of chief complaints : 86 cases were nasal obstruction, 55 cases were rhinorrhea and 50 cases were headache. 5) Clinical findings in nasal cavities : 61 cases had rhinorrhea, 35 cases had deflected nasal septum and 55 cases had hypertrophy and polypoid change on nasal mucosa etc. 6) 49 cases had Caldwell Luc's op. combined with other operations, such as polypectomy, ethmoidectomy and S.M.R. 7) In this series the total number of similar findings between the roentgen diagnosis and transillumination and operative findings were 85 cases out of 105 surgery cases. 8) In 4 cases (3.8%) which showed highly pathologic roentgen and transillumination findings, they had normal or minimal pathologic operative findings. 9) In 16 cases (15.2%) which showed mild and minimal pathologic roentgen findings, they had highly pathologic operative findings. Among them 12 cases had strongly positive reaction by transillumination.