To investigate the antioxidant and anti-inflammatory effects of alpha-lipoic acid (ALA) in the treatment of endometriosis in an experimental rat model by evaluating biochemical and histopathologic parameters. Experimental endometriosis was induced by the peritoneal implantation of autologous endometrial tissue. The rats were randomly divided into two groups with eight rats each. Group I was intraperitoneally administered ALA 100 mg/kg/day for 14 days. Group II was intraperitoneally administered saline solution at the same dosage and over the same period. Endometrial implant volume was measured in both groups both pre- and post-treatment. Tumor necrosis factor alpha (TNF-) was measured in peritoneal fluid. Total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) were assessed in serum. The implants were histopathologically evaluated. In the ALA group, the serum TOS and OSI levels, the endometrial implant volumes, the TNF- levels in serum and peritoneal fluid, and the histopathologic scores were significantly lower compared to the control group (P < 0.05). Alpha-lipoic acid may have a therapeutic potential in the treatment of endometriosis due to its antioxidant and anti-inflammatory effects.