This study investigated the radical scavenging activity and effect in liver function enzyme markers alanine aminotransferase (ALT) of flavonoid extract from the leaves of himbabao. Tests for physical, chemical and infrared characteristics of the prepared himbabao extract confirmed that it is a flavonoid. The antioxidant activity of the flavonoid extract of himbabao was determined through in vitro tests using 1, 1-diphenyl-2-picryl hydrazyl (DPPH), nitric oxide and superoxide scavenging assays, in comparison with standard antioxidants – ascorbic acid, quercetin and silymarin. The effectiveness of the Himbabao flavonoid extract as a hepato protective agent was measured by its ability to normalize ALT level using carbon tetrachloride (CCl4) induced hepatotoxic Wilstater rats. The hepato protective activity of the extract was compared to the standard hepato protective agent, Silymarin. The flavonoid extract of himbabao showed an antioxidant activity in concentration dependent manner when tested directly using DPPH, nitric oxide and superoxide scavenging assays. The three doses (40 mg/kg, 100 mg/kg, 200mg/kg) of the flavonoid extract of himbabao were able to lower down the ALT level of the CCl4- induced rats in similar effect. Therefore, the flavonoid extract of himbabao possesses antioxidant and hepato protective activities.