Acute compartment syndrome (ACS) is a condition typically associated with long bone fractures or severe trauma; however, non-traumatic etiologies also occur. We describe a case of an otherwise healthy female pediatric patient presenting with unilateral forearm pain without an inciting injury. Intracompartmental pressures of the forearm were measured and she was diagnosed with idiopathic compartment syndrome. Our goal is to encourage clinicians to consider acute compartment syndrome even in the absence of trauma.