1-Ricinoleoyl-2-acyl-sn-glycero-3-phosphocholinewas prepared by incorporating ricinoleic acid completely in the sn-1 position of egg and soya phosphatidylcholine ( PC) using immobilized phospholipase A(1) as the catalyst. The optimum reaction conditions for maximum incorporation of ricinoleic acid into PC through transesterification were 10% (w/w) immobilized enzyme ( 116 mg), a 1: 5 mol ratio of PC ( soya, 387 mg; egg, 384 mg) to methyl ricinoleate ( 780 mg) at 50degreesC for 24 h in hexane.