Four experiments examined the effects of inhibition of return on endogenously generated and visually guided saccades. In Experiments 1-3, subjects responded to a peripheral target by making either a prosaccade (toward the target) or an antisaccade (toward the field opposite the target). Prior to the appearance of the target, one of the two equiprobable target locations was activated by presenting a peripheral precue (Experiments 1 and 2), or by executing an endogenous saccade in response to a central precue (Experiment 3). In Experiment 1, the eyes remained fixed when the cue appeared; in Experiment 2 subjects made a saccade to the peripheral cue, and returned their eyes to the centre before the target appeared. In both experiments, saccade latencies were longer for targets appearing at the precued location for both prosaccade and antisaccade tasks. In Experiment 3, saccade latencies were longer for targets appearing at the precued location only in the prosaccade task; no effect of the precue was obtained in the antisaccade task. These results suggest that endogenously generated saccades activate both an inhibition of target detection and a motor alternation bias. Experiment 4 showed that inhibition of return generated by a peripheral precue increased the latency for a subsequent endogenous saccade (from a central, arrow target) toward the precued location. Inhibition of return may affect perceptual processing and also produce a motor alternation bias dependent upon whether it is activated exogenously or endogenously.