Molecular responses to Cd were studied in roots of three pea genotypes (cv. Frisson, VIR4788, VIR7128) growing in a polluted substrate. Root and shoot fresh biomass was decreased by Cd pollution in all genotypes. Gene expression profiling after one weeks' exposure to Cd revealed that genes encoding stress-related proteins (heat-shock protein, pI206, chitinase, chalcone isomerase), a metallothionein, γ -glutamylcysteine synthetase and glutathione reductase were up-regulated in the pea genotypes. A glutathione synthetase gene was activated only in VIR4788 but a homoglutathione synthetase gene was unaffected by Cd, and concomitantly glutathione/homoglutathione accumulation in plant roots did not change with Cd stress. However, the overall concentration of thiol groups, which indicate the presence of phytochelatins and/or homophytochelatins, increased more than 2-fold.