In patients with symptomatic aneurysms of the posterior communicating artery, the prognosis of oculomotor palsy mainly depends on the interval between the onset of palsy and the time of operation, and furthermore on the degree of preoperative deficit and the development of the cranial nerve lesion. The incidence of ultimately complete or incomplete palsy is the same in cases with subarachnoid haemorrhage and without rupture ("warning symptom"). In many cases, an initially incomplete paresis develops to a complete ocular palsy within eight days. Ptosis is generally the first symptom, and it frequently shows the earliest recovery of all other disturbed oculomotor functions after surgery. Full recovery of oculomotor palsy occurs usually only in those patients who undergo early clipping of an aneurysm, i.e. mainly within 10 days after onset of ocular palsy. Complete restitution after carotid ligation is possible, but rare. In cases with full recovery, restitution occurs mostly within three months, sometimes even within a few weeks. An improvement in oculomotor palsy is still possible after a year, but ultimately in these patients recovery remains always more or less incomplete. Incomplete restitution of a third cranial nerve lesion is very often associated with aberrant regeneration and subsequent synkinetic ocular movement. The restitution of the single ocular muscle functions shows a fairly constant course: the levator palpebrae muscle and the M. rectus medialis show rapid recovery. The parasympathetic fibres follow next, but normal function of elevation and depression of the ocular bulb (M. rectus sup., M. obliquus inf. and M. rectus inf.) is often delayed.