We have developed a repressible seed-lethal (SL) system aimed at reducing the probability of transgene introgression into a population of sexually compatible plants. To evaluate the potential of this method, tobacco plants were transformed with an SL construct comprising gene 1 and gene 2 from Agrobacterium tumefaciens whereby gene 1 was controlled by the seed-specific phaseolin promoter modified to contain a binding site for the Escherichia coli TET repressor (R). The expression of this construct allows normal plant and seed development but inhibits seed germination. Plants containing the SL construct were crossed with plants containing the tet R gene to derive plant lines where the expression of the SL construct is repressed. Plant lines that contained both constructs allowed normal seed formation and germination, whereas seeds in which the SL construct was separated from the R gene through segregation did not germinate. The requirements of such a method to efficiently control the flow of novel traits among sexually compatible plants are discussed.