Routine clinico-radiologic procedures are most frequently performed by otolaryngologist for diagnosis of the chronic maxillary sinusitis. However, the plain X-ray pictures are sometimes confusing in diagnosis of the chronic maxillary sinusitis. But the accuracy of the radiologic diagnosis about the disease of the maxillary sinuses as diagnostic technique used with contrast media got improved and we came to know the function of the mucosa of the maxillary sinuses. The authors performed a radiologic mucous memorane function test to the patient of the chronic maxillary sinusitis from August 1978 to January 1979. The results were as follows ; 1. The normal was found in 46 cases (27.7%), the(+) in 54 cases (32.2%), the () in 21 cases (12.7%), the () in 7 cases (4.2%) and the cloudy in 38 cases (22.9%) in the plain film. The complete type in 53 cases (31.9%) the incomplete type in 38 cases (22.9%), the spotted type in 10 cases (6.0%), the transitional type in 32 cases (19.3%), the localized type in 26 cases (15.7%) and the scattered type in 7 cases (4.2%) in the radiologic mucous membrane function test. 2. Relationships between the plain film and the radiologic mucous membrane function test were as follows ; I) The normal and the (+) in the plane film showed complete type (51%) incomplete types (35%) a lot. II) The () showed transitional (57%) and spotted (24%) a lot. III) The () showed transitional (29%) localized (29%) and scattered (24%) a lot. IV) The cloudy in the plain film showed a lot in localized (55%). So more thinner of the mucous membrane of the maxillary sinus, more in complete and incomplete type. 3. Duration of drainage of the contrast media in the maxillary sinus was shortest when the contents of the maxillary sinus were absent, was longest when purulent, and intermediate when seromucous. 4. The relationships between the plain X-ray and drainage time of the contrast media were; It was percentages that had been drained within 7 days. I) The normal was drained in 37 cases (88.1%) and the (+) was in 32 cases (68.1%). II) The () was drained in 9 cases (56.3%) and the () was in 4 cases (57.1%). III) The cloudy was drained in 19 cases (47.5%). So more thicker of the membrane of the maxillary sinus, more prolong the drainage time of the contrast media. 5. The relation-ships between the X-ray mucous membrane function test and drainage time of the contrast media were ; I) The complete type was drained within 7 days in 87.2% and within 10 dyas in 100%. II) The incomplete type was drained within 7 days in 80% and within 10 days in 97.1%. III) The spotted type was drained within 7 days in 54.5% and within 10 days in 90.0%. IV) The transitional type was drained within 7 days in 42.4% and within 10 days in 63.6%. V) The Localized type was drained within 7 days in 37.5% and within 10 days in 50%. 6. The relationships between the X-ray mucous membrane function test and the contents of the maxillary sinus were ; I) When the contents of the maxillary sinus were absent, complete type (48.0%) and next incomplete was most common type (25.7%). II) When the seromucous, the incomplete type (30%) was most common and next the spotted type (20%) and localized type (20%). III) When purulent, the localized type (48.9%) was most common and next the transitional type (37.2%) and scattered type (11.6%) in order.