During the meeting held on 17-19 September 1997 in Brest, some potential uses of marine microorganisms were examined in order to assess current knowledge. Communications reported in this publication refer principally to the substances found in these microorganisms: in particular to long chain polyunsaturated fatty acids produced by bacteria, cyanobacteria and microalgae; enzymes, focusing on those stable at high temperatures, from deep sea bacteria; polysaccharides from bacteria; other substance presenting biological activities that could be of interest for pharmaceutical, food, feed or cosmetics industries and for preventing marine fouling and contamination by heavy metals. Some general aspects have also been examined, such as methods and means for microalgae strain holding, research of biological activities, culture of those microorganisms, and purification of molecules. Industrial issues related to these developments were presented by representatives from some relevant industries.