The white matter of resected temporal lobes from patients with intractable complex partial seizures shows increased cellularity which appears to be related to glia and neurons. This study, using quantitative methods, defines an increase in glial cell numbers and a significant increase in glial nuclear size within a defined area of white matter in the lateral temporal lobe. Evaluation was made on specimens from ten patients with complex partial seizures compared with two patients with non-epileptic brain lesions and five autopsy patients with no neurologic disease. The importance of recognizing these alterations in glia and the possible relevance to the pathoetiology of epilepsy are discussed.