Two polygalactolipids, designated as components A and B, were isolated from spinach chloroplasts and were also obtained from glycolipid products synthesized with chloroplast enzymes using uridine diphosphate galactose as a galactose donor. These lipids were purified by column and thin layer chromatography. Chemical analysis of component A indicates that the lipid is trigalactosyl diglyceride, whereas component B behaves like tetragalactosyl diglyceride on a thin layer plate. The major fatty acid in trigalactosyl diglyceride was alpha-linolenic acid. Relative amount (molar ratio) of galactolipids in spinach chloroplasts was monogalactosyl diglyceride:digalactosyl diglyceride:trigalactosyl diglyceride:(tetragalactosyl diglyceride) = 60:30:5:1.