Phospholipase D from Streptomyces effectively catalyzed the transfer reaction of the phosphatidyl residue from 3-sn-phosphatidylcholine to the 5'-hydroxyl group of nuclesides in a two-phase system. Thus, a variety of 5'-(3-sn-phosphatidyl)nucleosides could be readily prepared in high yields by means of this reaction. Among them, phosphatidyl-FUR (3b), phosphatidyl-Ara FC (8b), and phoshatidyl-neplanocin A (12b) each produced a significant increase in the life span mice bearing i.p.-implanted P388 leukemia, being more effective than the parent nucleosides.