The occipital horns of the lateral ventricles are of different lengths in approximately 70% of unselected neurological patients, with the left being longer in approximately 57% and the right horn being longer in about 13%. In right-handed neurological patients with asymmetric occipital horns, the left horn is 5 times more likely to be long than is the right. In left-handed neurological patients with asymmetrical occipital horns, longer right occipital horns occur as often as longer left occipital horns. In patients with recurrent focal cerebral seizures, occipital horn length does not correlate with handedness or with speech dominance, probably because many of these patients had injuries to the brain in early life.