Leptogium (Ach.) Gray is distributed throughout South Korea; however, for nearly two decades no detailed taxonomic or revisionary research on this lichen genus has been conducted. This study examined the specimens deposited in the lichen herbarium at the Korean Lichen Research Institute, and samples were identified using descriptions recently published in the scientific literature. In this revisionary study, a total of fourteen species of Leptogium were documented, including new records of Leptogium delavayi Hue, Leptogium denticulatum Nyl., and Leptogium trichophoroides P. M. J${o}$rg. & A. K. Wallace. Detailed descriptions of each species are given, including their morphological, anatomical, and chemical characteristics. A key to all Leptogium species known to occur in South Korea is also presented.