In rabbits exposed for 3 and 6 months to 1 mg/m3 of metallic nickel dust, the increase of pulmonary phospholipids was about 3 and 4 times, respectively. The corresponding increase of phospholipids in lung lavage was about 6 and 11 times, respectively. A detailed study of the phospholipid composition in lung lavage from the rabbits exposed for 3 months showed an increased amount of nonacidic phospholipids and a decreased amount of phosphatidylglycerols. Although most of the increase was due to the disaturated phosphatidylcholines, the relative increase was highest for the ether analogs of phosphatidylethanolamines. In the exposed rabbits the two ether analogs, 1-alk-1'-enyl-2-acyl- and 1-alkyl-2-acyl-sn-glycero-3-phosphoethanolamines, constituted 10.4 and 8.2%, respectively, of the phosphatidylethanolamine fraction. The corresponding values in the control rabbits were 5.2 and 0%, respectively. The occurrence of 1-alkyl-2-acyl-sn-glycero-3-phosphoethanolamines and the increase of 1-alk-1'-enyl-2-acyl-sn-glycero-3-phosphoenthanolamines indicate that the biosynthetic synthetic pathway of ether lipids may be stimulated in the exposed rabbits. This is of interest since a high proportion of ether lipids is observed in many tumors and since some nickel compounds may give respiratory tumors.