Technical Abstract: Maize transposable elements, Activator (Ac) and Ds have been transformed into several heterologous plant species for transposon tagging of genes and they have been successfully used to taf and to clone genes in Arabidopsis, flax, pentunia, tobacco, and tomato. To investigate the possibility of transposon tagging and subsequent cloning of carrot genes, carrot was transformed with modified maize transposable elements Acativator-transposase (Ac-transposase) gene and Ds using Agrobacterium tumefaciens strain LBA 4404. Callus initially transformed with Ac-transposase was then transformed with Ds. Transgenic carrot calli and plants carrying only Ds or both modified Ac and Ds were analyzed for transposition of Ds. Ds did not transpose in any of the transgenic plants carrying Ds only. On the other hand, excision of Ds was detected in all of tissue culture-regenerated plants carrying both Ac-transposase and Ds. Reinsertion of Ds into new chromosomal sites was detected in transformed plants based on Southern blotting and sequence analysis of Ds insertion sites using TAIL-PCR. Our results indicated that Ds will transpose in the carrot genome if Ac-transposase is present and could be used for transposon tagging of carrot genes.