The purposes of this study was 1) to assess the plantar flexion and dorsiflexion peak torques (PT) of the ankles at 30, 90 and 240.. s-1 in 101 patients (86 men, 15 women) who had been operated on for unilateral, complete closed Achilles tendon (AT) rupture at Oulu University Hospital, Oulu, Finland, in the period 1987-1992, 2) to determine whether comparison between the legs shows any impairment, 3) to study whether the weakness is speed-dependent, 4) to determine at what angular displacement of the ankle the weakness is manifested, 5) to study how the results correlate with age, type of operation and follow-up time. The Lido Multi-joint II dynamometer was used for the measurements. There was no significant dorsiflexion weakness detectable upon comparison between the legs, but the mean relative peak torque deficits in the injured limb were 8.4, 9.0 and 3.0% at 30, 90 and 240.. s-1 respectively for the men and 15.0, 16.6 and 6.4% for the women. The mean percentage torque differences were significantly greater in the women at all the test speeds (p