In the course of investigations on lupin alkaloids in the family Leguminosae, (-)-(trans-4'-hydroxycinnamoyl) lupinine (III) was found in extracts of young seedlings of Lupinus luteus, with no detectable amount in mature or immature seeds or later plant growth stages; its concentration increased rapidly during the first 4-8 days of seedling growth (25-30°C, both dark and daylight) and then gradually decreased. This communication reports new enzymatic systems in Lupinus seedlings capable of forming III from (-)-lupinine (I) and trans-4-hydroxycinnamic acid (II) in the presence of ATP and CoA as cofactors. Enzyme preparations were obtained from hypocotyls of L. luteus seedlings grown in the dark for 5-6 days (via homogenization, centrifugation, ammonium sulfate precipitation, Dowex 1-treatment, and Sephadex G-25 desalting). Reaction mixtures containing I, II, CoA, ATP, MgSO4, etc., were incubated, and the product was confirmed as III by chromatographic comparison (HPLC, TLC) with natural material and Dragendorff's reagent reaction. The product was not formed without ATP/CoA or when the enzyme preparation was preheated (100°C, 15 min), indicating the enzymatic system requires a heat-labile factor, with absolute requirements for ATP and CoA, and partial requirement for Mg ion.