An analysis was perfomed on 32 operative cases of Achilles tendon disease. Two patient classifications emerged. One group suffering an acute rupture of the Achilles tendon with no antecedent complaints, and the second group had a history of chronic pain, weakness and functional loss. This latter group could be further differentiated by the occurrence of tendon failure in 10 of 22 cases. Surgical exploration in the group with chronic complaints demonstrated a high incidence of diffuse reactive changes such as fibrinoid and myxomatous degeneration, fibroisis and metaplastic calcification. Degenerative disease of the Achilles tendon should be recognized and treated not as a simple injury but as a pathological lesion.