Background and purpose: Allicin has a wide range of pharmacological functions, all of which can be demonstrated in anti-inflammatory, antioxidant, antifungal and anti-tumor activities. In this research, we investigated the neuroprotective role of allicin in the process of diffuse traumatic brain injury and its effect on interleukin levels and histological changes in rats. Materials and methods: In this experimental study, Wistar rats (n=56) underwent diffuse controlled brain injury by Marmarou method, and 30 minutes later, the drug was injected intraperitoneally at different doses. Veterinary Coma Scale was used and Beam Walk and Beam Balance movement and balance tests were taken at pre-traumatic times, immediately after recovery from the trauma, and 24, 48, and 72 hours after the trauma. Results: Findings showed that allicin at 25 mg/kg and 50 mg/kg can reduce these differences compared to the control group (Sham and Intact) (P