A new enzyme, UDP-glucose : saucy! alcohol glucosyltransferase, was purified 110-fold from Gardenia jasminoides cell cultures. The enzyme catalyzes position-specific glucosylation of saucy! alcohol to form salicin using UDP-glucose as a glucose donor. The molecular weight of the enzyme as estimated by gel filtration is 51,000. Apparent Km values for saucy! alcohol and UDP-glucose are 0.11 and 0.03 1 mM, respectively. The enzyme shows a pH optimum between 9.0 and 9.5. Sulfhydryl inhibitors and some divalent cations inhibit the enzyme activity. The glucosyltransferase exhibits a strict substrate specificity for salicyl alcohol.