We studied the alterations of MDA and three forms of SOD activities such as T-SOD, CuZn-SOD, and Mn-SOD in rat cerebral tissues injected by bordetella pertussis (BP) to elucidate protective mechanism of SOD against the infectious brain injury. The results were that water content(WC), Evans blue content(EB), MDA, and Mn-SOD activities in 4 h and 24 h BP-treated groups increased and T-SOD and CuZn-SOD decreased compared to corresponding normal saline(NS)-treated groups, respectively(P < 0.01); MDA increased and had a positive correlation with WC and EB in 4 h BP treated group (r = 0.9650, r = 0.9441, P < 0.01, P < 0.01, respectively); Mn-SOD activities were elevated and had a negative correlation with WC, EB, and MDA (r = -0.8650, r = -0.9021, r = -0.9346, P < 0.01, P < 0.01, P < 0.01, respectively) in 24 h BP-treated group. The results suggest that the increase of component Mn-SOD activities may play an important role in vivo endogenous protective mechanism against delayed infectious brain injury.