Abstract The transfer of phosphatidyl choline between liposomes was stimulated by the protein fractions from spinach leaves, etiolated and greening leaves of Avena seedlings. This is confirmed by the transfer of [ 14C]phosphatidyl choline or spin-labeled phosphatidyl choline between donor and acceptor liposomes. ESR spectrum changes also indicated that no spin-labeled phosphatidyl choline was released from donor liposomes by spinach leaf protein unless acceptor liposomes were present. [ 14C]phospholipids were transferred from liposomes to both spinach chloroplasts and Avena etiochloroplasts by phosphatidyl choline exchange protein from germinated castor bean endosperms and further from liposomes to spinach chloroplasts by spinach leaf protein. These results support the view that phosphatidyl choline in the plastid is supplied from the synthesis site, the endoplasmic reticulum, by phospholipid exchange protein.