We observed postictal pleocytosis in 7 of 62 cerebrospinal fluid specimens obtained from 27 patients with epilepsy. Each patient had a known seizure disorder; none had any other cause for the pleocytosis. The maximum number of leukocytes was 12/mm3; the maximum number of erythrocytes was 190/mm3. Postictal pleocytosis was more common in samples obtained within 12 hours of the last seizure. Although previous studies have emphasized that pleocytosis is more common after repetitive generalized tonic-clonic seizures, we found increased leukocyte counts in cerebrospinal fluid after single simple, complex partial, or generalized tonic-clonic seizures.