Abstract: The present study was aimed to evaluate the stem bark aqueous extract of Psidium guajava for modulatory effect against CCl4 induced liver damage in rats. A total of thirty six male rats, were randomly divided into six groups of six rats each. The extract was administered orally for 15 days at 125, 250 and 500 mg kg-1 b.wt. The results obtained showed that treatment with the extract significantly (p<0.05) restored liver weight. There was significant (p<0.05) increase in the level of Packed Cell Volume (PCV), haemoglobin (Hb) and Red Blood Cell (RBC) counts and significant (p<0.05) decrease in White Blood Cell (WBC) counts compared to toxin control group. Also administration of the extract caused significant (p<0.05) decrease in the activities of Alanine Transaminase (ALT), Aspartate Transaminase (AST), Alkaline Phosphatase (ALP) and the level of total bilirubin and significant (p<0.05) increase in total protein level compared to toxin control group. Similarly the extract caused a significant (p<0.05) increase in the activities of Catalase (CAT) and Superoxide Dismutase (SOD) and significant (p<0.05) decrease in reduced Glutathione (GSH) and Thiobarbituric Reactive Substances (TBARS) level compared to group 2 (toxin control group). The histopathological study indicated that treatment with the extract restored and regenerated hepatic cells compared to toxin control group. This study found that administration of aqueous stem bark extracts ameliorated hepatotoxicity induced by CCl4 in rats.