Selected variables related to the stress response in mammals, such as cortisol, metallothionein (MT), glutathione (GSH) and lipid peroxidation measured as thiobarbituric acid-reactants (TBARs) were evaluated in rainbow trout in order to establish whether chemical stress by cadmium exposure or physical stress by handling cause a significant response and comparable effects between stressors. The results obtained show about three times higher levels of liver MT in fish exposed to cadmium as compared to controls and twice as high after stress, whereas plasma cortisol levels increased significantly both after stress and cadmium exposure. This indicates that both MT and cortisol were sensitive indexes to stress in this species. In contrast, liver cytosolic GSH was affected only by cadmium treatment and liver TBARs remained unaffected.