The composition of fatty acids in suspension-cultured cells from the liverwort Marchantia polymorpha L. grown at 25 and 15 o C was analyzed. The liverwort cells grown at 25 o C contained approximately 18% linolenic acid (18:3ω3), 11% arachidonic acid (20:4ω6) and 3% eicosapentaenoic acid (20:5ω3) as percentages of total fatty acids. When the cells were grown at 15 o C, the relative amounts of 18:3 and 20:5 showed a large increase, while those of other fatty acids were less affected. Subcellular fractionation experiments showed that the levels of 20:4 and 20:5 were increased in the chloroplast fraction but not in the extrachloroplast fraction, while the level of 18:3 was increased in both fractions. Lipid analysis revealed that galactolipids were present in chloroplasts, PE (phosphatidylethanolamine) in the extrachloroplast fraction and PC (phosphatidylcholine), PG (phosphatidylglycerol), PI (phosphatidylinositol) and DAG (diacylglycerol) in both compartments. Of lipid species bound to 20:5, only MGDG (monogalactosyldiacylglycerol) and chloroplastic PC were increased by low temperature.