A small collection of ESts was generated from the bark of the rubber tree clone RRIM 2025. Low molecular weight metal-binding proteins, metallothioneins(MTs), were found to be very abundant in the bark gene expression profile. Multiple sequence alignment and phylogenetic analysis between three Hevea MTs and other plant MTs identified then as type 2 and type 3 proteins. Semi-quantitative PCR analysis indicated that each MT was differentially expressed between bark, leaves and latex, with the lowest transcript abundance in latex. In latex from ethephon-treated trees, all MT isoforms were induced at four hours after treatement while only one of them showed decreased expression sfter 24 hours. Our findings indicate the existence of a multiple gene family for Hevea MTs and Varying roles played by isoforms derived from different rubber tree tissues.