A major strategy for controlling pest insects is the development of plants resistant to insect attack.  Introduction of proteins toxic to insects into plants via genetic engineering is one approach to developing such plants.  We have previously cloned and characterized the DNA encoding the insecticidal crystal protein gene of Bacillus thuringiensis strain HD-73.  To transfer the toxic crystal protein gene into plants, the HD-73 gene was engineered 3' to the (ORF 24) promoter of pTi1595.  This promoter/gene cassette was cloned into a binary micro T-DNA vector containing a plant selectable marker and delivered into tobacco cells.  In regenerated transgenic tobacco plants, we have detected B. thuringiensis peptides by immunoassay.  Crystal protein-specific transcripts in these tissues are truncated at the 3' end of the gene.  Nonetheless, leaves of some transgenic plants kill tobacco hornworms in feeding bioassays.