This paper examines acoustic cues of Korean word-internal stops from the production and perception tests. Korean word-internal lax, aspirated and tense stops were mainly distinguished by closure duration and H1-H2 cues rather than VOT or F0 cues which function as major cues for the contrast of Korean word-initial stops. For the word-internal stop contrast, VOT and F0 cues were weakened or neutralized, but the closure duration cue was somewhat strengthened by its more significant differences among the three stops: the ratios were 1:2.4:2.9. In addition, 50% of lax stops were voiced during their closure. The primary role of the closure duration in perception was confirmed through the stop identification test: 90% of the consonant portions with short closure duration were identified as lax stops. The distinctive values of H1-H2 among the three stops were observed and also contributed to the identification of Korean word-internal stops, especially aspirated vs. tense stops. (Pai Chai University)