Fourth research Efficacy of L-Carnitine Against Mesterolone Induced Toxicity on the Pancreas of Adult Albino Rats. ABSTRACT Background: The anabolic steroid drugs usage increased dramatically among the young athletes, resulting in many toxic effects, especially, acute pancreatitis and cardiovascular toxicity. Lcarnitine (LC) supplementation in different models has anti-inflammatory and antioxidant roles. Aim of the work: To examine the ameliorative role of LC against mesterolone toxic effect on pancreas in adult albino rats. Material and methods: thirty-six rats were randomly assigned into 4 groups: Group I (control) 18 rats were equally presented into 3 subgroups; group Ia (no treatment), group Ib (0.5 mL corn oil), Ic (1 mL distilled water), Group II (LC) 6 rats received 350 mg/kg/day, group III (mesterolone) 6 rats were given 2.14 mg/kg/day and group IV ( combined ;LC and mesterolone) 6 rats received the same doses as mentioned above. All treatments were received by oral gavage for 4 weeks. Finally, rats were sacrificed; serum obtained for measuring malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), amylase and lipase levels, and blood samples for fasting blood glucose (FBG). Pancreatic tissues were prepared for histopathological ,immunohistochemical and morphometric analysis of tumor necrosis factor receptor -associated factor 6 (TRAF6) and heme oxygenase-1 (HO-1). Results: Mesterolone caused redox imbalance, functional and structural damage of pancreatic tissue and increased TRAF6 and HO-1 immune-expression. In the combined group, LC co-administration mitigated redox imbalance, improved functional and structural damage of pancreatic tissue and decreased TRAF6 and HO-1 immune-expression. Conclusion: Co-administration of LC provides a protective role against mesterolone induced pancreatic toxicity through antioxidant and anti-inflammatory effects