This study assessed maximum eccentric (ECC) and concentric (CON) torque of quadriceps (QUAD) and hamstring (HAM) muscle groups in healthy females (n = 13) and males (n = 27). Peak torques (PT) of bilateral muscle actions were recorded at constant angular velocities of 0.52, 1.57 and 2.61 rad.s-1. The QUADCON and HAMCON PT decreased (p less than 0.05) with increasing angular velocity. The QUADECC and HAMECC PT increased (p less than 0.05) in females, whereas QUADECC PT decreased (p less than 0.05) and HAMECC PT showed no change in males. In general, ECC PT was higher (p less than 0.05) than CON PT and QUAD PT was higher (p less than 0.05) than HAM PT, for any given angular velocity. Males displayed higher (p less than 0.05) PT than females but when PT were adjusted for body mass the sex differences in QUADCON and HAMCON were reduced (p less than 0.05), whereas the differences in QUADECC and HAMECC were abolished. The CON and ECC PT were, on average, 60% and 41% greater, respectively, in males than in females. The corresponding differences, when adjusted for body mass, were 23% and 8%. ECC:CON PT for QUAD were higher (p less than 0.05) in females than in males. CON and ECC HAM:QUAD PT ratio increased (p less than 0.05), as a function of velocity. This study suggests, that bilateral ECC PT is higher than CON PT and CON HAM:QUAD PT ratio is higher than ECC HAM:QUAD PT ratio.(ABSTRACT TRUNCATED AT 250 WORDS)