PurposeTo assess the long-term ultrasonographic appearance of rupture of the Achilles tendon.Subjects and MethodsWe examined 70 patients at an average of 63 months (range 10–120 months) after rupture of the Achilles tendon. We assessed the patient's contralateral tendon and also performed ultrasonography on the Achilles tendon of 70 age- and sex-matched controls. We recorded the maximum transverse anteroposterior diameter, the presence of intratendinous alterations, and the presence of intratendinous calcification.ResultsThe average maximum anteroposterior diameter of the ruptured tendon was 11.7 mm (SD = 2.10). The patients' normal tendons measured an average of 5.4 mm (SD = 0.9), and there was an average measure of 4.9 mm (SD = 0.5) (p = 0.0001) in the controls. There was no difference in the maximum anteroposterior diameter of the ruptured tendon depending on the method of treatment (conservative, open repair, percutaneous repair). Seventeen patients exhibited areas of hypoechogenicity in their ruptured tendon, two patients had areas of hypoechogenicity in their unruptured contralateral tendon, and 10 patients had calcification in their ruptured tendon.ConclusionThe anteroposterior diameter of the ruptured tendon was significantly greater than the nonruptured contralateral. However, when compared with a group of individually age- and sex-matched controls, the patients' contralateral tendons had significantly greater maximum anteroposterior diameter and had a greater prevalence of intratendinous alterations. This difference may represent a background of subclinical tendinopathy that may predispose to rupture.