Phytochelatins (PCs, (gamma Glu-Cys)(n)-Gly, n = 2-11) are metal ions-binding peptides produced by plant, algae and fungi. Antibodies that recognize PCs were induced by the injection of Balb/c mice with a multiple antigen peptide consisting of PC6 (MAP-PC6). One stable hybridoma producing a monoclonal antibody (mAb), designated as 4-9C, was established. The DNA sequences of the heavy and light chain variable regions of the 4-9C mAb were determined. The 4-9C mAb had a smaller equilibrium dissociation constant (K-d) towards Cu-, Zn- and Ni-PC7 complexes than those towards other metal-PC7 complexes and free PCs.