Abstract: The levels of lipid peroxides, glutathione, vitamin C, vitamin E catalase and superoxide dismutase enzymes were measured in the livers of Schistosoma mansoni infected mice (CD strain weighing 20-25 g) at different durations post infection (1, 2, 4, 6 and 8 weeks). Moreover, the liver weight, body weight, liver to body weight and total protein were studied in the same animal groups. Control non-infected groups were run simultaneously with each infected mice group. The data obtained showed that lipid peroxides were elevated throughout the different durations of infection while glutathione decreased with infection. On the other hand, both vitamins C and E showed a reduction in the livers of mice during the different durations of infection. The activity of catalase showed an insignificant change after one and two weeks and a high significant decrease in the livers of four, six and eight weeks S. mansoni infected mice, while, superoxide dismutase significantly decreased one and two weeks post infection with a significant elevation four, six and eight weeks post infection. Moreover, a significant reduction was observed in body weight after four, six and eight weeks of infection accompanied with an elevation in liver weight only after six and eight weeks. Consequently, liver weight/body weight showed an elevation after four, six and eight weeks of infection. Finally, the protein content was significantly lower at one, six and eight weeks post infection with S. mansoni. It could thus be concluded that host-parasite association results in production of free radicals as a result of an oxidative stress where the parasites struggle to overcome the immune response of the host and changes in host liver antioxidants occur as a means to scavenge these radicals.