In a series of papers, Slater, Beard and Glithero (1963) reported on a group of 69 patients who had suffered from a schizophrenia-like psychosis at some time after the onset of an earlier but continuing epilepsy. They gave a number of arguments, which need not be considered here, to support the view that the epileptic and the schizophrenic states were not independent of one another and merely coincidental, but that the pre-existing epileptic state was the direct cause of the schizophrenia-like illness, and that this could in fact be regarded as a special form of an epileptic psychosis, which took on for a time the appearance of a (symptomatic) schizophrenia. One of the arguments on which reliance was placed was that there was a non-random relationship between the ages of onset of the epilepsy and of the schizophrenia, such that the interval between the two varied about a mean of 14 years. The three clinical groups into which the 69 patients were classified had significantly different mean ages of onset of epilepsy of 20·5, 16·3 and 9·3 years respectively; but there was no significant difference between the three clinical groups in respect of the mean interval between onset of epilepsy and onset of psychosis, 15·6, 14·0 and 12·8 years respectively. In fact, in the case of the duration of epilepsy, with an F value of 0·24, between-group variance was only a fraction of the within-group variance.