Aim: The present study was conducted to investigate the protective effect of chamomile fl owers methanolic extract (CFME) and fennel seeds methanolic extract (FSME) on azathioprine (AZA), an immunosuppressant drug, which induced a liver injury and oxidative stress in rats. Methods: Rats were divided into 6 groups (8 rats each) and treated orally for 28 consecutive days as follows. Group 1: rats were given normal saline and used as controls; group 2: rats treated with CFME (200 mg/kg); group 3: rats treated with FSME (200 mg/kg); group 4: rats treated with AZA (25 mg/kg); and groups 5 and 6: rats treated with CFME (200 mg/kg) or FSME (200 mg/kg) 15 min prior to AZA (25 mg/kg) treatment. At the end of experimental period, blood and liver samples were collected from all groups for biochemical analysis and histological examination. Results: The obtained data revealed that AZA-induced hepatic injury in the rats as evidenced by the signifi cant increase in serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, cholesterol, and direct bilirubin as well as hepatic malondialdehyde level accompanied with signifi cant decrease in reduced glutathione content and total antioxidant capacity in the liver. Moreover, body weight gain showed the signifi cant decrease and relative liver weight showed the signifi cant increase on AZA treatment. The sequential signifi cant changes in biochemical parameters were accompanied by severe histological changes in the liver tissue, including hepatocytes disorganization with pyknotic nuclei, fatty degeneration, congestion, fi brosis, and bile duct necrosis around the portal tract. The areas of hemorrhages in blood vessels and in between hepatocytes were also seen. However, the results showed the potential hepatoprotective effects of CFME and FSME against AZA-induced liver injury and oxidative stress. They succeeded in restoring the biochemical parameters and improving the histological picture of the liver. This improvement was more pronounced in the rats pretreated with FSME. Conclusion: It could be concluded that CFME and FSME have hepatoprotective potentials against AZA probably due to their antioxidant properties and radical scavenging activity.Key words: Azathioprine; chamomile fl owers; fennel seeds; liver; oxidative stress Preventive role of chamomile fl owers and fennel seeds Preventive role of chamomile fl owers and fennel seeds extracts against liver injury and oxidative stress induced by an extracts against liver injury and oxidative stress induced by an immunosuppressant drug in rats immunosuppressant drug in rats This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.