Objectives: Occupational/industrial exposure and experimental intoxication of mercury can produce neurological effects but Pteleiosis suberosa stem bark extract (PTSSBE) might be useful in the treatment of brain disorders because it's anti-ulcer, anti-inflammatory and antioxidant effects had been documented. Methods: The present study was therefore designed to investigate some phenolic constituents, evaluate its antioxidant properties and examine its reversal effects of PTSSBE on sub-acute mercury-induced brain toxicity. Rats were divided into five groups of 10 animals each. Group I was given distilled water; group II, III, IV and V was orally administered with mercury at a dose of 3.75 mg/kg body weight. Group III, IV and V were co-treated with PTSSBE of 25, 50 and 100 mg/ kg body weight respectively, for 10 days. Results: The results revealed that the stem bark extract exhibited high presence of antioxidants. Experimental exposure of rats to mercury significantly decreased the activities of catalase (CAT), lactate dehydrogenase (LDH), and the level of reduced glutathione (GSH), while the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and the formation of malondialdehyde (MDA) were increased. These effects were reversed by co-administration with PTSSBE in mercury-induced brain toxicity in rats. Conclusion: The protective effects of Pteleiosis suberosa, during mercury exposure suggest that these phenolics and PUFAs may be helpful in treating neurological disorders and other related cerebral toxicity implicated in depleted cellular ATP and oxidative stress.