Double-labelled phosphorylethanolamine with a [32P]//[14IA1 ratio of 1 was incubated in vitro with rat liver slices prepared from control and ethanol-intoxicated rats, and the radioactivity measured at given time intervals in liver ethanolamine, phosphorylethanolamine, phosphatidylethanolamine and phosphatidylcholine. Evidence is presented that after 10 and 15 minutes phosphorylethanolamine enters the slices as an intact molecule, which is directly converted into lipid forms by the Kennedy's pathways. At longer times a hydrolysis of the ester occurs which lowers considerably the theoretical [32P]/[14C]ratio. Fatty liver slices produced by acute ethanol intoxication uptake from the medium more phosphorylethanolamine than controls, and hydrolyze less efficiently than controls the phosphoric ester to ethanolamine and inorganic phosphate.