Background: To investigate the protective effects of rosmarinic acid in rats exposed to hepatic ischemia/reperfusion injury. Materials and methods: Thirty-two rats were randomly classified into four groups of eight rats each: laparotomy without medication, rosmarinic acid (dose of 50 mg/kg via oral gavage) followed by laparotomy, laparotomy followed by hepatic ischemia/reperfusion, and hepatic ischemia/reperfusion with rosmarinic acid. Serum aspartate aminotransferase, alanine aminotransferase, and malondialdehyde levels and total oxidant activity and total antioxidant capacity levels of the liver, lung, and kidney were assessed. The histopathologic assessment was also performed. Results: Rosmarinic acid significantly reduced liver function test parameters and decreased oxidative stress and abnormal histopathologic findings in the liver. The oxidative stress in the lung significantly increased in the ischemia/reperfusion group but significantly decreased in the ischemia/reperfusion + rosmarinic acid group due to the addition of rosmarinic acid. Rosmarinic acid led to no reduction in oxidative stress in kidney following hepatic ischemia/reperfusion injury. There were no statistically significant differences among the groups regarding histopathologic changes in kidney and lung sections. Conclusions: Rosmarinic acid has antioxidant properties and is an effective hepatoprotective agent. However, although rosmarinic acid provides useful effects in the lung by increasing antioxidant capacity and reducing oxidative stress after ischemia/reperfusion injury, it does not ameliorate histopathologic changes. These findings suggest that rosmarinic acid is likely to provide favorable outcomes in the treatment of hepatic ischemia/reperfusion injury. Background: To investigate the protective effects of rosmarinic acid in rats exposed to hepatic ischemia/reperfusion injury. Materials and methods: Thirty-two rats were randomly classified into four groups of eight rats each: laparotomy without medication, rosmarinic acid (dose of 50 mg/kg via oral gavage) followed by laparotomy, laparotomy followed by hepatic ischemia/reperfusion, and hepatic ischemia/reperfusion with rosmarinic acid. Serum aspartate aminotransferase, alanine aminotransferase, and malondialdehyde levels and total oxidant activity and total antioxidant capacity levels of the liver, lung, and kidney were assessed. The histopathologic assessment was also performed. Results: Rosmarinic acid significantly reduced liver function test parameters and decreased oxidative stress and abnormal histopathologic findings in the liver. The oxidative stress in the lung significantly increased in the ischemia/reperfusion group but significantly decreased in the ischemia/reperfusion + rosmarinic acid group due to the addition of rosmarinic acid. Rosmarinic acid led to no reduction in oxidative stress in kidney following hepatic ischemia/reperfusion injury. There were no statistically significant differences among the groups regarding histopathologic changes in kidney and lung sections. Conclusions: Rosmarinic acid has antioxidant properties and is an effective hepatoprotective agent. However, although rosmarinic acid provides useful effects in the lung by increasing antioxidant capacity and reducing oxidative stress after ischemia/reperfusion injury, it does not ameliorate histopathologic changes. These findings suggest that rosmarinic acid is likely to provide favorable outcomes in the treatment of hepatic ischemia/reperfusion injury.