Herpes simplex encephalitis typically involves the medial temporal and inferior frontal lobes; brainstem lesions are very unusual. We present a 42-year-old woman admitted with delirium and diagnosed as herpes simplex encephalitis. The patient had gadolinium-enhancing inferior frontal and pontine lesions on magnetic resonance imagings. The patient was successfully treated without any neurologic sequelae, though contrast-enhancement was still present. This case report emphasizes that herpes simplex encephalitis should be investigated in the differential diagnosis of brainstem lesions. Moreover, contrast-enhancement may persist for some months even after clinical improvement.