The Achilles tendon is the largest and strongest tendon in the body, yet one of the most commonly injured. Tendon degeneration is a relatively common disorder, predisposing to tears and often associated with paratenonitis. Numerous other diseases involve the Achilles tendon, some with classic imaging appearances, others with non-specific appearances. The aim of this pictorial essay is to review the radiographic, computed tomographic, ultrasonographic and MR appearances of the normal and diseased Achilles tendon.