The purpose of this study is to investigate the production of English vowels by native speakers of Korean. In the production test, two English speakers and four native Korean speakers served as subjects. The four native Korean speakers were divided into two groups, experienced and inexperienced. Native English speakers generally showed significant differences both in vowel duration and in F1 & F2 values between members of vowel pairs which are of special interest of this study: /i/l vs. /I/, /$varepsilon$/ vs. /${ae}$/, and /u/ vs. /$mho$/. The overall results showed that the experienced group produced more accurate results in vowel duration, F1, and F2 values.