Background Oculomotor palsy is a common complication in patients with posterior communicating aneurysm.This study was conducted to investigate the postoperative recovery of patients with posterior communicating aneurysm complicated with oculomotor palsy and to analyze the factors influencing length of recovery.Methods From 2000 to 2006,148 patients with posterior communicating aneurysm were treated at our hospital,with 74 of them having concurrent unilateral oculomotor palsy.All of the patients underwent craniotomy after the diagnosis by means of whole-brain digital subtraction angiography (DSA).The patients were divided into two groups for observation of postoperative recovery during the follow-up period.Patients in group A were treated with simple pedicle clipping of the aneurysm while patients in group B were treated with pedicle clipping of the aneurysm and decompression of the oculomotor nerve.Results Of the 40 patients in group A.20 underwent surgery within 14 days and completely recovered from oculomotor palsy in 10-40 days.Fourteen patients underwent surgery within 14-30 days.of whom 12 completely recovered within 30-90 days and 2 cases recovered incompletely.The remaining six patients underwent surgery after more than 30 days:of these.four patients recovered completely and two recovered incompletely.Of the 34 cases in group B,15 underwent surgery within 14 days and completely recovered from oculomotor palsy in 10-40 days.Sixteen patients underwent surgery in 14-30 days.of whom 14 completely recovered in 30-90 days and 2 recovered incompletely.The remaining three patients underwent surgery after more than 30 days,of whom two patients recovered completely and one recovered incompletely.Conclusions Early diagnosis and surgical treatment of patients with unilateral oculomotor palsy induced by posterior communicating aneurysm are important to full postoperative recovery of the oculomotor nerve.No correlation was found,however,between decompression of the oculomotor nerve,such as excision or puncture of the aneurysm,and postoperative recovery time.