Seventy-two lichen specimens of Cetrelia collected in South Korea since 2003 were examined by both phenotypic and phylogenetic analyses. The phenotypic analysis was based on morphological and chemical characters, and the phylogenetic analysis was based on nrDNA ITS sequences. The result suggested that the presence and absence of isidia, soredia, lobules and medullar reaction C+ or C- are the important characters in the taxonomy of this genus. Four species of Cetrelia, C. chicitae, C. braunsiana, C. japonica, and C. pseudolivetorum have been identified in this study. Description of each species is presented with morphological and chemical characters. A key to the Cetrelia species is also presented.