The cDNAs encoding the zeta class of glutathione S-transferases (GSTs) (GSTZs), which are multifunctional enzymes, were cloned from Arabidopsis thaliana L. and three lines of Brassica napus L. by RT-PCR, and named AtGSTZ for A. thaliana ecotype Columbia gl1, and BnGSTZ-A, BnGSTZ-B and BnGSTZ-C for B. napus cv. Shan 2A, Shan 2B and Ken C1, respectively. Sequence analysis revealed that the sequences of Shan 2A and Shan 2B were identical, and Ken C1 was different only in 3.8% of the sequence. Comparison of these sequences with published sequences in GeneBank showed that the sequences of the Brassica species were unpublished. The cDNAs were then inserted into two vectors for in vivo expression in Escherichia coli and in vitro expression in a wheat-germ cell-free protein synthesis system. All GSTZs were well expressed both in vivo and in vitro as an enzymatically active form, showing that all of them had both dichloroacetic acid dechlorinating and maleylacetone isomerase activities.