Despite many years of investigation of the convulsive therapy process, there is still much controversy concerning the importance of the seizure itself. Most studies have concluded that the convulsion is a necessary index of cerebral change essential to clinical behavioral change.9,10,15,33,39 Some investigators, nevertheless, have assigned significance not to the seizure but to such factors as the psychological meaning of the treatment to the patient, feelings of fear, and the repeated loss of consciousness.3,4,28 The early studies of Kalinowsky et al.24 and Pacella et al.,30 demonstrating both clinical and electrographic differences between grand mal and petit mal treatments indicated the significant role of the seizure. The various studies comparing convulsive with subconvulsive treatment demonstrated that techniques culminating in a convulsion were uniformly associated with measurable degrees of neurophysiologic and behavioral change, while subconvulsive techniques were not15,27,38-40 In recent studies from this laboratory, similar