Bacterial beta-glucuronidase gene (GUS) has been introduced into tobacco by means of Agrobacterium tumefaciens/binary vector system. Northern analysis and enzyme assay for GUS from the regenerated tobacco following A. tumefaciens infection indicated that GUS has been successfully transferred into tobacco and expressed. Northern bands for GUS from the transformed plants were at the mRNA size of ca. 2.4 kb, and spectrophotometric analysis for the enzymatic activities of the plant extracts for beta-glucuronidase showed a peak at ca. 400 ㎚ indicating beta-glucuronidase activities in the transformed plants.