The purpose of this study is to investigate the perception and production of English vowels by native speakers of Korean. In perception test, twelve English vowels /${\ae},{\;}a,{\;}{\Game},{\;}e,{\;}{\varepsilon},{\;}i,{\;}I,{\;}a,{\;}o,{\;}u,{\wedge},{\;}{\mho}$/, as in had, hard, hoard, hayed, head, heed, hid, hod, hoed, whod, Hudd, and hood produced by native speakers of English were used as perception test materials and subjects were asked to identify the vowels. Two different groups of subjects participated in the perception test. One consisted of 90 students who were taking an English phonetics course, and the other consisted of 64 who were not. The results showed that the former did better than the latter m identifYing English vowels, and that vowels in 'head' and 'had' were relatively hard to identify, while vowels in 'hayed', 'hard', and unexpectedly, 'heed' and hid' were easy to perceive. In production test, two native English speakers and 4 native Korean speakers served as subjects. The 4 native Korean speakers were divided into two groups as in the perception test, experienced and inexperienced, depending on whether they were taking an English phonetics course or not. Native English speakers generally showed significant differences both in vowel duration and in FI & F2 values between members of the vowel pairs which are of special interest of this study: /i/ vs. /I/, /${\ae}$/ vs. /$\varepsilon$/, and /u/ vs. and /$\mho$/. There was no significant difference between the two Korean groups. Native Korean speakers showed much difference in neither duration nor FI & F2 values except significant durational difference in /i/ vs. /I/ pair.