A series of observations of phytoplankton were made at seven station with two control stations in Inchon Dock to clarify the quantity, quality and standing crop of phytoplankton from Oct. to Nov., 1976. Thirty seven species of phytoplankton, representing 18 genera, 36 species, 1 forma were taken in this research. Chaetoceros decipiens, Rhizosolenia delicatula, Hemiaulus sinensis, Chaetoceros affinis and Skeletonema costatum were the dominant species in this area during two moths. By the ecological division, the neritic species occupied 86.5% of total phytoplankton composition. Standing crop of phytoplankton represented much variation: ranging from 263 to 1, 614, 832 cells/l. The maximum happened at station 1 on November