Fifty-three of 57 patients who had evidence of bitemporal epileptiform abnormalities and who required investigation with stereotactic depth electroencephalography (SDEEG) recordings to determine the site of origin of seizures underwent surgical resection for the treatment of their epilepsy. A minimum of 2 years' follow-up was available in 48 patients who underwent a temporal lobe resection. In this group, 19 patients (40%) were greatly improved, and of these 14 (29%) became seizure free and 5 (10%) had no more than 3 seizures each year. Another 22 patients (46%) showed a worthwhile reduction in seizure frequency of at least 50%. Seven patients (15%) were not significantly improved. An etiological factor of early convulsions before age 3 (usually febrile) was associated with a better outcome. Both the lack of a strong predominance for SDEEG-recorded seizures to arise in the resected temporal lobe and the presence of residual epileptiform abnormalities in the postexcision electrocorticogram were correlated with poorer results.