Object The purpose was to investigate the effect of neutralizing interleukin (IL)-6 antibody treatment on the activity levels of Na+-K+/Mg+2 adenosine-5′-triphosphatase (ATPase) and superoxide dismutase (SOD) in brain after experimental subarachnoid hemorrhage (SAH) in the rat. Methods Seventy adult male Wistar rats weighing 280 to 310 g were used in this study. The animals were randomly allocated to groups: group 1 (n=10) consisted of normal controls; group 2 (n=20) underwent microsurgical exposure of the atlantooccipital membrane and normal saline injection into the cisterna magna, but no blood injection; and the remaining 40 rats were subjected to injection of the blood-cerebrospinal fluid mixture into the cisterna magna. Immediately after mixture injection, each of these 40 rats was randomly assigned to either the mixture injection-only group (group 3, n=20) or the mixture injection plus IL-6 antibody treatment group (group 4, n=20). Results Two doses of IL-6 antibody affected the levels of SOD and Na+-K+/Mg+2 ATPase when testing was carried out on day 2 after mixture injection. On the other hand, administering 5 doses of the antibody resulted in a significant decrease in SOD level and a significant increase in Na+-K+/Mg+2-ATPase activity compared with those seen in the mixture injection-only subgroup on day 5 after experimental SAH. Conclusions The results of this study show that IL-6 antibody may be a beneficial treatment for peroxidation damage in long term after experimental SAH.