Anesthesia acutely impairs superoxide dismutase (SOD) but not catalase activity. The activities of SOD and catalase were measured in fresh homogenates of subicular and thalamic tissues obtained from P7 rat pups immediately after 6 h of anesthesia or sham treatment and are expressed in units per milligram of protein. (A) We found a significant 2-fold decrease in SOD activity immediately after anesthesia treatment compared to that in sham controls (**P = 0.0011) (n = 6 pups in the control group; n = 6 pups in experimental group). (B) There was no difference in catalase activity between the sham control and experimental groups (P = 0.6631) (n = 6 pups in the control group; n = 6 pups in the experimental group). P7 = postnatal day 7.