Ethanol at concentrations up to 5% (v/v) had no effect on the growth of Schizosaccharomyces pombe, whereas concentrations over 7.5% were inhibitory. The major membrane phospholipids in S. pombe cells growing aerobically in the absence of added ethanol were phosphatidylinositol, phosphatidylcholine and phosphatidylethanolamine. Oleic acid (18:1) was the main fatty acid. When ethanol (7.5%) was added to aerobically growing cultures, the phosphatidylinositol content increased, whereas the 18:1 content decreased. Similar changes were observed in the membrane phospholipids of cells grown anaerobically without ethanol. However, the presence of ethanol in anaerobically growing cultures had an opposite effect on fatty acids, as the 18:1 content increased. The results support the idea that ethanol tolerance in S. pombe may be connected with a high content of 18:1 fatty acids, and with the ability to maintain a high rate of phospholipid biosynthesis.