The statistical properties of depth spiking in the interictal EEG were assessed in 12 patients with intractable temporal lobe epilepsy in whom electrodes had been stereotactically implanted for diagnostic purposes. Prior to the implantation surgery each patient was administered a battery of neuropsychologic tests. Correlational analyses showed that the total amount of depth spike activity (TA) negatively correlated with measures of intelligence, while the laterality of the spike activity (LAT) appeared to be positively related to a memory score and the degree of psychologic independence. The results of this study are consistent with previous findings of a significant relationship between surface EEG recordings and performance. In addition, our data suggest a relationship between specific neuropsychologic functions and the patterns of in-depth EEG epileptiform discharges.