As summer is upon us, we thought a discussion of tennis leg would be beneficial to our fellow clinicians. Tennis leg is a relatively common clinical condition, classically manifesting as acute, sports-related pain in the mid-calf. First described in 1883, the pathogenesis has been debated--tennis leg was first attributed to rupture of the plantaris tendon, though more recent investigations have implicated rupture of the medial head of the gastrocnemius at its myotendinous junction. For simplicity, many authors use the term tennis leg to describe all such acute muscle injuries in the superficial calf.