The purpose of this study was radiographic analysis of the morphology of maxillary sinus in adolescents and adults. In order to analize the morphology of maxillary sinus in view point of anteroposterior width of medial wall, vertical distance between antral floor and nasal floor level, anterior extension, distance between antral floor and maxillary 1st molar apex, and types of lower border of maxillary sinus, specialized maxillary projection and periapical view with paralleling technique was taken. The author examined orthopantomograms and intraoral standard views taken from 400 adolescents and adults ranged 15-65 year-old. The obtained results were as follows: 1. The antero-posterior width of medial wall of maxillary sinus was 32.80mm in 15-19 year-old group, 33.86㎜ in 20-24 year-old group, 34.09㎜ in 25-29 year-old group, and 33.67㎜ in 30-65 year-old group, and the left maxillary sinus was somewhat smaller than the right. 2. The vertical distance between antral floor and nasal floor level was 8.49㎜ in 15-19 year-old group, 9.05㎜ in 20-24 year-old group, 8.95㎜ in 25-29 year-old group, and 8.32㎜ in 30-65 year-old group. 3. The order of anterior extension of maxillary sinus were distal half of canine, mesial half of canine, mesial half of 1st premolar, and distal half of 1st premolar. 4. The distance between antral floor and maxillary 1st molar were 4.36㎜ in 15-19 year-old group, 4.77㎜ in 20-24 year-old group, 3.58㎜ in 25-29 year-old group, and 2.33㎜ in 30-65 year-old group. 5. The order of the types of lower border of maxillary sinus were entire downward type, close type, partially downward type, waving type, separating type, and indistinct. In the types of antral floor, there was a tendency to increase the seperating type with age.