The present study was designed to investigate lipid metabolism in whole blood cells, bone marrow cells and reticulocytes. In order to do this, the in vitro incorporation of (14)C-acetate Na into gross lipid fractions, major lipid fractions and total fatty acids were studied and were compared with serum lipids levels and fatty acid composition. The experimental animals used were rabbits which were made anemic by the injection daily for 7 days of 0.3ml, per kilo of body weight of acetylphenylhydrazine. Results were as follows. 1) Serum lipid levels were significantly higher in the treated group than in the control, though there was no difference in the composition of serum fatty acids between them. The lipemia after acute hemorrhage may be release from bone marrow. In the composition of serum fatty acids of bone marrow cells and whole blood cells, the percentage of linoleic acid was decreased in the treated group. This decrease may be connected with reticulocytosis in hemolytic anemia. 2) (14)C-incorporation by blood cells of the treated group into total lipid was significantly increased than control. 3) In the percentage distribution of (14)C into major lipid classes of the treated group, it was found that (14)C was significantly incorporated into free cholesterol and decreased into none esterified fatty acid than in control. 4) In regard to the study on the distribution of (14)C-acetate in individual fatty acid separated by gaschromatography, the percentage of the radioactivity recovered in myristic acid and palmitic acid was significantly increased but was decreased in 200 carbon and more longer chain fatty acids in whole blood cells of the trated group. 5) The reticulocytes (but not mature erythrocytes) are capable of synthesizing lipids has been demonstrated by the incorporation of (14)C-acetate into the lipids of rabbit reticulocytes. Reticulocytes have ability of lipids synthesis in de novo and elongation system.