A radiological study on sesamoid bones of hands and feet was done in korea adults who visited the CapitalArmed Forces General Hospital of korea during last 10 months from Jan. 1, to Oct. 30, 1979. The incidence ofpresence or absence of sesamoid bones in each possible site and shape and partition were studied in 250 males and200 females. The results are as follow; 1. In hands, two sesamoids are present at metascarophalangeal joint ofthumb in all and one at metacarpophalangeal joint of little finger in half, metacarpophalangeal joint of index,interphalangeal joint of thumb. metacarpophalnageal joint of middle finger and metacarpophalangeal joint of ringfinger were other sites, in order of frequency. 2. In feet, two sesamoids are present at metatarsophalangeal jointof great toe in all, but the incidence at other sites are much lower comparison to hands and the sites areinterphalnageal joint of great toe, metatarsophalangeal joint of 5th toe, metatarsophalangeal joint of 2nd toe,and metatarsophalangeal joint of 4th toe in order frequency. 3. In comparision with sexes,the incidence is alittle greater in female at every site. 4. In general, the partition line of sesamoid bone is transverse, andfracture line of sesamoid is longitudinal. 5. In comparison with Europians, the incidence of sesamoid bone atinterphalangeal joint of thumb and great toe is about half and at other sites, except metacarso phalangeal jointof thumb and great toe, the incidence was smaller in each site.