We used the magnetic search coil technique to measure the horizontal cervico-ocular reflex (COR) of 8 subjects in response to transient or sinusoidal (0.1-1.0 Hz) trunk rotations while their heads were firmly immobilized. Although we were able to resolve eye rotations of < 0.05 degrees, the COR was hardly measurable (gain was always < 0.07). This finding, made with the most precise measurement technique used to date, suggests that the COR makes a negligible contribution to the stability of gaze in normal subjects during natural activities.