Collema Weber ex F.H. Wigg is scarcely scattered throughout South Korea. However, a detailed taxonomic or revisionary study has not been carried out for almost two decades. The present study was based on specimens deposited in the lichen herbarium at Korean Lichen Research Institute, which were identified using recent literature. In this revisionary study, a total of sixteen species of Collema, including five new records, C. furfuraceum var. luzonense, C. pulchellum var. subnigrescens, C. rugosum, C. subconveniens, C. tenax, and one variety C. leptaleum var. leptaleum were documented. Further, detailed descriptions of each species and their morphological, anatomical and chemical characteristics and a key to all known Collema species of South Korea were reported.