Today's world is increasingly seeking ways to replace the synthetic drugs with the therapeutic power of natural products. This study was designed to investigate the protective effects of Foeniculum vulgare (FV) and Salvia officinalis (SO) waters infusions against carcinogen chemical trichloroacetic acid (TCA)-exposure in rats. The chemopreventive potential of the plant infusions were evaluated by measuring levels of serum marker enzymes [aspartate aminotransferase (AST), alanin aminotransferase (ALT), creatine phosphokinase (CPK), acid phosphatase (ACP), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH)], antioxidant defense systems [Reduced glutathione (GSH), glutathione reductase (GR), superoxide dismutase (SOD), glutathione-S-transferase (GST) and catalase (CAT)] and lipid peroxidation level (Malondialdehyde = MDA) in various tissues of rats. Female Sprague-Dawley rats, weighing 150-200 g, were randomly allotted into four experimental groups. While the control group (A) received only natural spring water, the treatment B group (0.2% TCA) supplied with the drinking water containing 0.2% TCA, the treatment C (TCA + FV infusion) and D (TCA + SO infusion) groups drank the drinking water containing 0.2% TCA and 2.5% the plant grains and leaves ad libitum for 50 days during experiment. At the end of the 50 days experiment, TCA and the plant's infusions caused different affect on the serum marker enzymes, tissues antioxidant defense systems and lipid peroxidation against TCA-exposed in rats with comparison to those of TCA exposed and control rats. According to the results, both TCA and TCA + plants infusions caused a significant increase in serum AST, ALT and CPK activity. Non-enzymic antioxidant GSH level significantly increased in the brain whereas reduced in the erythrocytes and kidney of TCA + FV and TCA + SO as compared to TCA group and control. While MDA content slightly increased in tissues of TCA group in comparison to those of control, significantly decreased in the brain, liver and kidney of rats of TCA + FV and TCA + SO groups as compared to TCA group and control. Antioxidative enzyme activity such as CAT and SOD significantly increased in the brain, liver and kidney tissues of TCA induced group whereas reduced the same enzymes activities as compared to TCA group. The ancillary enzyme GR activity significantly depleted in the brain and kidney of TCA + FV and TCA + SO groups in comparison to those of TCA exposed and control rats. In addition, the drug metabolizing enzyme GST activity significantly declined in the brain and kidney of TCA + FV and TCA + SO groups in comparison to those of TCA exposed and control rats, whereas, also reduced in the liver of TCA + FV and TCA + SO groups in comparison to those of TCA exposed rats. It was concluded that the levels of serum marker enzymes were found not to be decreased in plants treated groups due to hepatic damage induced by TCA. Also the four antioxidant enzymes were found to be activated in different degrees following TCA treatment and declined the activation of the enzymes the plant infusions accompanied by significant reduction in MDA concentration in the tissues. The observations, along with changes, might suggest that the both FV and SO may possess antioxidant properties during the period of a 50-day protective exposure.