Leg pain in the athlete is common and has many different etiologies. The most common causes include muscle or tendon injury, medial tibial stress syndrome, stress fracture, and exertional compartment syndrome. Less common causes of leg pain include lumbosacral radiculopathy, lumbosacral spinal stenosis, focal nerve entrapment, vascular claudication from atherosclerosis, popliteal artery entrapment syndrome, and venous insufficiency. This article reviews the essential history and physical examination findings and the various causes of leg pain to help the clinician pinpoint the diagnosis and facilitate the athlete's return to sport participation.