The metabolism of phosphatidylethanolamine (PE) was studied in male rats fed a low methionine diet for 7 days with or without supplemental choline. Groups of animals were injected with 2‐¹⁴C‐ethanolamine and killed at intervals thereafter up to 72 hr. Liver phospholipids were isolated, and PE and phosphatidylcholine (PC) were separated by argentation chromatography into diene (18∶2), tetraene (20∶4) and hexaene (22∶6) fractions. Fatty acid composition and the distribution of radioactivity and specific activity in the total phospholipids and in the fractions were determined. Choline deficiency did not affect total liver phospholipid, but it did increase the amount of PE and decreased that of PC. The major effect of the deficiency on phospholipid fatty acids was to decrease the proportion of PE arachidonate and to increase that of docosahexaenoate. Ethanolamine incorporation into liver PE of deficient rats was only slightly less than in the controls, but loss of the radioactivity from the PE was slower. Ethanolamine radioactivity appearing in the PC of deficient rats was about half that of the controls, even though specific activities of the PE precursors were similar to the control rats. Choline deficiency increased the biological half‐lives of the total PE and its fractions. Although the proportion of PE tetraenoic fraction was reduced, the total amount of this liver PE fraction in deficient rats was not affected. However the amount of hexaenoic fraction was doubled, and it accounted for most of the increased quantity of liver PE seen in deficient animals. The results suggested that in choline deficiency PE synthesis was delayed but not appreciably suppressed, and that limited availability of methionine for methylating the PE fractions in their proper proportions affected the concentrations of the PE fractions and impaired their normal conversion to PC.