The ocular refraction of the rabbit was determined by inserting spherical lenses of between -3 and +4D and measuring the relative VECP amplitude in response to checkboard patterns of 21 min arc. The rabbit's eye was found to be almost emmetropic (+0. 5D ). The contrast sensitivity function of the rabbit's visual system was determined by recording the VECP in response to reversed gratings of different spatial frequencies. The contrast sensitivity was found to be highest at 0.35 c/deg with an upper cut-off frequency at 3 c/deg, corresponding to a grating acuity of 10 min arc.