Chronic exertional compartment syndrome of the lower leg is a well-described and documented cause of exercise-related pain in recreational, elite, and military athletes. Although this condition is common, the exact underlying mechanisms, those most at risk, long-term effects on muscular strength if unrecognized, and prevention strategies are relatively uncertain. Runners are most commonly affected and can be markedly impaired by the recurrent, often predictable pain that develops with exercise. An accurate history, high index of suspicion, and compartment pressure testing before and after symptomatic exercise confirms the diagnosis. Conservative therapy is minimally effective. Fasciotomy is the treatment of choice for athletes who are unwilling to modify their exercise or sport.