To obtain eicosapentaenoic acid-producing bacteria, some 3,500 strains of bacteria were isolated from the intestine of marine animals from sea around the Korean peninsula. Forty two eicosapentaenoic acid-producing bacteria were obtained through screening with TLC and gas chromatography, and the strain with highest content of eicosapentaenoic acid (up to 33% of total fatty acid when grown at 5 degrees C) as the sole polyunsaturated fatty acid was identified as an Aeromonas sp. on the basis of physiological properties.