The data are based on a study of 300 adult individuals of all ages between the 20-80 age groups chosen atrandom sample from Hanil Hospital from 1973 to 1977. Of these adult were asymptomatic with no apparentradiographic abnormality in stomach and duodenum. Over 3,000 measurements were made for this study also. Theresults were as follows ; 1) Hypotonic type ; The incidence of this type was 36.7% with high incidence in female,especially in old individuals. The height of duodenal bulb is higher than other type. 2) Hypertonic type ; Theincidence of this type was 30.7% with same incidence in male and female. The maximal vertical internal diameter ofduodenal loop is longer than other types and minimal measurement of outer margin of 2nd portion of duodenum toposterior margin of vertebral bodies is shorter than other types. 3) J-Shaped type ; The incidence of this typewas 18% with same incidence in male and female the distance between pylorus and anterior margin of spine is longerthan other types. 4) Casecade type ; The incidence of this type was 14.6% with high incidence in male and notpropotion with age. The maximal vertical internal diameter of duodenal loop is ihorter than other types andmaximal horizontal internal diameter of duodenal loop is longer than other types.