Metabolism of major lipids in E. floccosum was studied with /sup 14/C-acetate as a precursor. Among the phosphatides, phosphatidylcholine exhibited the maximum rate of synthesis and degradation, followed by phosphatidylethanolamine and phosphatidylserine. These phospholipids appear to exist in two pools, one metabolically more active than the other. In neutral lipids, maximum uptake was observed in triglycerides, followed by free fatty acids, diglycerides and monoglycerides. However, on chase of the labelled lipids, a continuous synthesis of all neutral lipid fractions was observed suggesting a recycling of the labelled carbon.