Current methods of evaluating seizure outcome after anterior temporal lobectomy (ATL) have major limitations. We evaluated the usefulness of a recently proposed system in our study of the stability of seizure frequency after ATL in 184 patients with intractable epilepsy. Data collection by chart review was supplemented by an intensive program of follow-up by our survey research center through correspondence or phone calls according to a protocol approved by our Institutional Review Board. Seizure frequency during each 12-month period after ATL was scored for each patient. The only statistically significant change in seizure frequency scores during follow-up was between the third and the fourth years (means of 2.61 and 2.11; P < 0.045). Further assessment showed that the change was most likely due to an increase in the proportion of patients who achieved a score of 0 when they successfully stopped taking antiepileptic medications (9.1% in the third year and 22.5% in the fourth year; P < 0.05). There was no statistically significant difference between follow-up years in the proportion of patients achieving excellent outcome (i.e. scores of 0-4). Outcome remained unchanged when follow-up at each year was confined to the same patients throughout their postsurgical course. By using the Seizure Frequency Scoring System, we have demonstrated that seizure outcome remains stable after ATL. The scoring system facilitates the detection of subtle changes in the postoperative course. The advantages and the limitations of the system are discussed.