Korean phonology has not recognised metrical foot as a phonological unit to account for certain phonological processes. This paper, however, suggests that an optional h-deletion process in Korean should require the notion of metrical foot as an independent phonological domain. The previous analyses rely on the notion of speech speed to explain optional h-deletion : i. e. an intervocalic h is deleted in fast speech, but in slow speech it remains. This paper claims that the notion of speech speed should be reinterpreted in terms of metrical foot : i.e. foot-internal t is deleted, but foot-initial h remains. Such analysis provides evidence that metrical foot constitutes a phonological unit in Korean phonology. With the notion of metrical foot, it enables us to achieve more detailed and accurate analysis of the optional h-deletion process in Korean.