Herpes simplex encephalitis is the most common form of encephalitis, but herpes simplex virus type 2 (HSV-2) encephalitis is very rare during pregnancy. In immunocompetent patients, HSV-2 encephalitis is usually mild. With early diagnosis and prompt initiation of antiviral treatment, as well as enhanced neurocritical care, a favorable outcome can be expected in both mother and neonate. We report a rare case of maternal HSV-2 encephalitis diagnosed by polymerase chain reaction following appendectomy. The woman had no symptomatic genital lesion, and the infant was not infected.