We report a 70-year-old man who developed theophylline-associated seizure with postictal fever and postictal pleocytosis. He was admitted to our hospital for a left hemiconvulsion lasting for two hours. The concentration of theophylline was high (21.6ng/ml), and electroencephalogram demonstrated periodic lateralized epileptiform discharges. Diffusion-weighted magnetic resonance imaging showed high signal intensity lesions in the right cingulated gyrus, insula and thalamus. Temperature above 38.0° was detected 5.5 hours after seizure and lasted for 60 hours. Cerebrospinal fluid (CSF) analysis on day 2 demonstrated pleocytosis (62/uL) with a predominance of polymorphonuclear leukocytes (90%). Temperature and CSF pleocytosis subsided after sedation. Intracranial inflammatory or infectious disease is the first consideration in epilepsy with fever and CSF pleocytosis, and then diagnosis of postictal fever and postictal pleocytosis should be made only by rigorous exclusion of that possibility.