UDP-glucose: coniferyl alcohol glucosyltransferase was detected in hypocotyls of spruce (Picea abies (L.) Karst.) seedlings. Enzyme activity rose after germination to maximal activity on about the 10th day and then rapidly declined. An antiserum against the glucosyltransferase isolated from cambial sap of spruce (Schmid and Grisebach, 1982, Eur. J. Biochem. 123, 363-370) was employed for localization of the enzyme in cross sections of hypocotyls from 10-d-old spruce seedlings, using the immunofluorescent technique. The results show that the transferase is located predominantly in the epidermal and subepidermal layers and in the vascular bundles. Intracellularly, the enzyme is located in the parietal cytoplasmic layer. The results corroborate the assumption that coniferin (coniferyl alcohol β-D-glucoside) participates in lignification of spruce.