The number of diabetes mellitus (DM) patients is one of the major concerns worldwide. As one of the main mechanisms of DM pathology is the involvement of oxidative stress, here we investigate the antioxidant capacities of frankincense (FRN) to treat or reduce the DM complications in the brain cortices of DM rats. Animals were segregated into four groups, the control group, FRN group given a dose of 500mg of FRN/kg for 5weeks, DM group given a single dose of 150/kg i.p of alloxan to induce diabetes and DM+FRN group given a single dose of 150/kg i.p to induce DM then followed by FRN 500mg/kg for 5weeks. The animals were sacrificed; their cerebral cortices were removed and used for biochemical and histopathological analyses.Alloxan treatment in the DM group showed significant reductions in catalase (CAT) activity and other non-enzymatic antioxidants i.e. thiol groups, concomitant with decreases in the levels of protein and albumin and increasing the level of uric acid. However, FRN administration to DM animals in DM+FRN group showed significant recovery of antioxidants, the thiol contents (total thiols, protein thiols and glutathione) of DM+FRN group have been increased as compared with DM animals (p<0.05). A recovery of CAT activity (p<0.05) to almost the levels of control rats with the recovery in protein and albumin levels (p<0.05) have been observed when FRN was administered. The uric acid level increased in DM group, came back to the levels of control after administration of FRN (p<0.05). We also observed that FRN reduces the histopathological damage caused by alloxan in DM+FRN group. It is concluded that FRN shows a beneficial effects that can reduce the oxidative damage caused by alloxan induced DM in the cortex of rats.