Herpes simplex virus (HSV) is a rare, antecedent infectious agent in Guillain-Barré syndrome (GBS). We report a patient with overlapping GBS and Bickerstaff's brainstem encephalitis (BBE). The patient had a vesicular lesion on her nose. Antecedent HSV type 1 (HSV-1) infection was confirmed by isolation of the virus and detection of the presence of serum anti-HSV-1 IgM antibody during the acute phase. Her serum IgG had high anti-GQ1b antibody titer. External ophthalmoplegia has been noted in 2 of 4 reported cases of HSV-associated GBS. Herpetic brainstem encephalitis cases of poor prognosis are known, but only 2 cases of benign brainstem encephalitis secondary to HSV infection, in which there was acute ophthalmoplegia and clinical features consistent with those of BBE have been reported.