We investigate whether a motion aftereffect (MAE) can be induced by an isoluminant stimulus which contains colour contrast but no luminance contrast. We created a red/green chromatic stimulus, composed of red and green monochromatic grating added in antiphase, and corrected for the chromatic aberrations of the eye. We varied the ratio of the red to green luminances in the stimulus and found that there is no luminance ratio at which the MAE disappears. The results suggest that isoluminant stimuli can induce a MAE which is as great and sometimes greater than that induced by luminance contrast.