Abstract: The results of determination of the changes in ODAP toxin, nucleic acid, protein and sugar content during development of Lathyrus sativus seed by microanalysis, show that the ODAP cotttent per seed increases accompaning with embryogenesis, and so the other macromolecular content. The DNA content per seed increases when the embryonic cells are rapidly dividing,especially the content of RNA, protein and starch is double during embryogenesis, and they increase even more quickly at the heart stage. If the content of DNA,ODAP and the soluble starch are determined by dry weight per gram, respectively, they present the declining tendency during the development of the seed, while the contents of other macromolecules increase only at the early stage, and arrive to the utmost almost at the heart stage, then begin to decline at the torpedo stage and decline to minimum until the embryo embryo defferentiate completely. Only the acidic protein keeps its increasing in all the time of embryo development.