Geriforte, a herbomineral preparation, feeding at 1 g% dose level for 4 weeks significantly increased catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities in liver of mice. In rats, in addition to these enzymes, the levels of reduced glutathione (GSH) were also significantly enhanced. However, only SOD in mice and, CAT and SOD activities in rat lung were significantly elevated after Geriforte treatment. A decrease in superoxide (O2-) and H2O2 release by alveolar macrophages obtained from rats fed on Geriforte containing diet was observed. The results suggest that Geriforte feeding stimulates antioxidant defense system and indicate the future preventive/therapeutic prospects of this preparation against free radical damage under various pathological states.