We investigated the activities of choline kinase, CTP: phosphorylcholine cytidyltransferase, and phosphatase during the greening of etiolated barley seedlings. Activities of choline kinase in leaves increased until 6 hours after illumination and decreased considerably after 6 hours, while activities of CTP: phosphorylcholine cytidyltransferase increased after illumination. On the contrary, changes of these two enzymatic activities showed reverse pattern in roots. The activities of phosphatase which hydrolyze phosphorylcholine decreased in leaves but changed little in roots during greening. The concentration of phosphorylcholine increased in xylem exudate and in roots during greening, while decreased in leaves. These results suggested that more phosphorylcholine arrive in leaves from roots as greening of etiolated barley seedlings.