Muscle derangements in athletes have a wide variety of causes, treatments, and prognoses. Given that the cause and severity of sports-related injuries may be difficult to determine clinically in some cases, MR imaging is utilized increasingly to evaluate muscle injuries in athletes. After reviewing useful MR imaging techniques, this article focuses on MR imaging of the most common causes of muscle pain and disability in athletes, including myotendinous strain, delayed onset muscle soreness, muscle contusion, myositis ossificans, muscle laceration, muscle herniation, and compartment syndrome. The differential diagnosis of various signal intensity abnormalities in muscle also is reviewed.