As a baseline survey to clarify the structure and function of bacterial populations in the intertidal waters of the Yellow Sea near Kunsan in 1987/1988, annual variation of bacterial number and biovolume was estimated by AODC method. Rod-shaped bacteria were more than 74% of all cells during the investigation period. Average biovolume of sampled bacteria ranged from ${3.19}pm0.59*10^{-2}$ to $6.19pm0.76*10^{-2}$ .$mu$$m^{3}$ for coccoid bacteria, and from 4.57.+-.0. $17*10^{-2}$ to $12.94pm0.21*10^{-2}$ .$mu$$m^{3}$ for rod-shaped ones. It showed that larger biovolume occurred at surface in case of coccoid bacteria, while at bottom in case of rod-shaped ones. There was little correlation between population density and biovolume. Diameters of edlls were below 0.5$mu$m among 77-89% of all measured coccoid bacteria, and lengthes of cells more than 70% of all measured rod-shaped ones were below $1mu$m. It explains the high percentage of "mini-bacteria" was distributed in the investigation area.tion area.