The purpose of this study was to evaluate the influence of knee joint range of motion (RoM) on the torque–velocity relationship and fatigue in the knee extensor muscles of 7 young (median = 26 y) and 7 older (68 y) adults. Each leg was assigned a RoM (35° or 75°) over which to perform a torque–velocity protocol (maximal isokinetic contractions, 60–300°·s⁻¹) and a fatigue protocol (120 maximal contractions at 120°·s⁻¹, 0.5 Hz). Six older participants were unable to reach 300°·s⁻¹ over 35°. Therefore, the velocity eliciting 75% of peak torque at 60°·s⁻¹ (V₇₅, °·s⁻¹) was calculated for each RoM from a fit of individual torque–velocity curves (60–240°·s⁻¹), and ΔV₇₅ (35°–75°) was determined. Fatigue (final torque/initial torque) was used to calculate Δfatigue (35°–75°). ΔV₇₅ was not different from 0 in young (−28.3°·s⁻¹ [−158.6 to 55.7], median [range], P = .091) or older (−18.5°·s⁻¹ [−95.0 to 23.9], P = .128), with no difference by age (P = .710). In contrast, fatigue was greater for 75° in young (Δfatigue = 25.9% [17.5–30.3], P = .018) and older (17.2% [11.9–52.9], P = .018), with no effect of age (P = .710). These data indicate that, regardless of age, RoM did not alter the torque–velocity relationship between 60 and 240°·s⁻¹, and fatigue was greater with a larger RoM.