Several factors are known to modulate the occurrence of interictal spike-wave complexes (SWC). During performance of a recent memory task by a patient with uncontrolled complex partial seizures and implanted electrodes, visually presented stimuli consistently evoked focal medial temporal lobe interictal SWC with an average latency of 228 +/- 29 ms. The SWC were more often lateralized to the left medial temporal lobe. No consistent change in interictal spike rate was observed during performance of several other cognitive tasks during which visual or auditory stimuli were presented. This suggests that performance of specific cognitive tasks--in this case, recognition memory of words--can trigger interictal SWC.