The effect of oral zinc (Zn) treatment was studied in the liver, kidneys and intestine of Long-Evans Cinnamon (LEC) rats in relation to metals interaction and concentration of metallothionein (MT) and glutathione (GSH). We also investigated the change in the activity of antioxidant enzymes and determined the biochemical profile in the blood and metal levels in urine. We showed that the Zn-treated group had higher levels of MT in the hepatic and intestinal cells compared to both untreated and basal groups. Tissue Zn concentrations were significantly higher in the Zn-treated group compared to those untreated and basal, whereas Cu and Fe concentrations decreased. The antioxidant enzyme activities in the Zn-treated group did not change significantly with respect to those in the basal group, except for hepatic glutathione peroxidase activity. Moreover, the biochemical data in the blood of Zn-treated group clearly ascertain no liver damage. These observations suggest an important role for Zn in relation not only to its ability to compete with other metals at the level of absorption in the gastrointestinal tract producing a decrease in the hepatic and renal Cu and Fe deposits, but also to MT induction as free radical scavenger.