Two different molecular markers, the plastid rbcL and mitochondrial cox1 genes, were used to define the taxonomic position of the northwest Pacific Ocean species currently named Gracilaria chorda. We analyzed both genes (1,222 bp for rbcL and 1,245 bp for cox1) from 18 specimens collected in Korea, Japan, and China. Phylogenetic reconstruction revealed that this organism should be classified in the genus Gracilariopsis, rather than in the Gracilaria. Thus, Gracilariopsis chorda (Holmes) Ohmi is the legitimate name for Gracilaria chorda Holmes. Within the species, the sequences differed by 8 bp (0.7%) in rbcL and 5 bp (0.4%) in cox1. Six haplotypes of cox1 tended to be geographically organized. Gp. chorda is characterized by coarse, elongate terete axes, short filiform branchlets usually at irregular intervals, an abrupt transition in cell size from medulla to cortex, cystocarps without tubular nutritive cells connecting the gonimoblast to the upper pericarp, and relatively large gonimoblast cells of the cystocarp in the specimens collected from Wando in southern Korea.