Thirteen patients who had ptosis surgery undertaken for disinsertion of the aponeurosis of the levator palpebrae superioris were reviewed. Pre-operatively all the patients had characteristic clinical signs of levator disinsertion which was confirmed at surgery and corrected by reposition of the disinserted aponeurosis. Five of these patients were initially mistakenly diagnosed as having a neurological cause for their ptosis. The diagnosis of this type of ptosis may easily be missed.