In Canada, 1 in 400 individuals live with multiple sclerosis (MS). MS is an autoimmune disease characterized by the attack of myelin in the central nervous system (CNS). This disease leads to motor dysfunction, pain, and cognitive impairments, among other debilitating symptoms. Currently, treatments are limited and are focused on stopping disease progression. The causes of MS are unclear but it is believed to be a multifaceted disease involving several contributors including smoking, low vitamin D levels, obesity, Epstein Barr Virus infection, and several gene candidates. A less commonly studied factor is mild traumatic brain injury (mTBI), and particularly injuries that are sustained at early life stages (i.e., adolescence). There is emerging evidence that those who experience mTBI earlier in life have an increased risk of developing MS. However, the mechanisms that underlie this connection have not been studied. To better understand the connection between MS and mTBI, we investigated the impact of repeated mild traumatic brain injury (RmTBI) during adolescence on MS-like pathology using the Lateral Impact Model (LIM) of mTBI and cuprizone (CPZ) feeding. We found that RmTBI results in motor performance changes and alterations in IBA1+ cell density in the corpus callosum of mice fed CPZ. The results from this study suggest that adolescent RmTBI may uncover motor deficits in a mouse model of MS and may exacerbate certain pathologies. These new data help to begin elucidating the clinical link established between mTBI and MS.