Herpes zoster infection may be complicated by motor involvement, the most common example of this being facial palsy in the Ramsay Hunt syndrome. Segmental lower motor neurone weakness is an uncommon disorder which does occur in the limbs, such paralysis usually occurring in the same segments as the dermatomes involved, or in those immediately contiguous. Nine cases of limb weakness are described, the weakness often being severe and accompanied by wasting and segmental reflex impairment. Long tract signs were absent. The cervical region was affected more commonly than the lumbosacral area. The prognosis for recovery was usually good. The condition reflects anterior horn cell or anterior nerve root involvement by the herpes zoster virus at the same or adjacent segmental levels as the sensory lesion.