A distinct syndrome of interictal behavior changes occurs in many patients with temporal lobe epilepsy. These changes include alterations in sexual behavior, religiosity, and a tendency toward extensive, and in some cases compulsive, writing and drawing. The concomitants of abnormal limbic acitivity therefore include behavior alterations as well as manifest seizures. The demonstration of interictal spike activity in temporal structures provides a pathophysiologic basis for this syndrome. The constellation of behavioral changes may be of great diagnostic value. In addition, it provides an example of a human behavioral syndrome assocaited with dysfunction at specific anatomic loci. The behavior syndrome of temporal lobe epilepsy may prove to be a useful model in studies on the neural substrates for behavior.