Marine algal flora and intertidal vegetation around Samchonpo power plant, south coast of Korea, were investigated at three sites, specially referred to the seasonal variation of the species from April to October, 1982. A total of 84 species were identified; 8 green, 19 brown and 57 red algae. Among three sampling sites investigated, 65 species were collected at the first site located in front of the power plant, 66 at the second site, Namildae beach, and 61 at the third, Sinsudo, respectively. The algal vegetation at the first site was dominated in cover by Sargassum thunbergii and Ulva pertusa in April, Corallina spp. Ulva pertusa in July, and Chondria crassicaulis and Ulva pertusa in October. At the second site, it was dominated in cover by Sargassum thunbergii, Gigartina tenella and Ulva pertusa in April, Sargassum thunbergii and Ulva pertusa in July, and Chondria crassicaulis and Ulva pertusa in October, whereas at the third site Sargassum thunbergii and Ulva pertusa in April, and Chondria crassicaulis in October, respectively. The biomass among three investigated sites showed 2,360 g-fresh wt/$m^2$ on an average; 283 g-dry wt/$m^2$ at the first, 277 g-dry wt/$m^2$ at the second, and 256 g-dry wt/$m^2$ at the third site, respectively.