Objective To investigate the clinical characteristics of posterior communicating artery (PcomA) aneurysm-induced oculomotor nerve paresis (ONP) before and after endovascular coiling,and provide a reference for diagnosis,treatment and prognosis of PcomA aneurysm-induced ONP.Methods A total of 55 patients with ONP attributable to PcomA,admitted to our hospital from July 2007 to January 2013,were chosen in our study;their clinical data and postoperative recovery were retrospectively analyzed to investigate clinical characteristics of ONP attributable to PcomA.Results The average preoperative paralysis time was 12.24±5.33 days in patients with complete preoperative paralysis and 8.90±3.51 days in patients with incomplete preoperative paralysis with significant difference (P=0.014).Of the 55 patients,31 (56.36％) had complete recovery ofoculomotor nerve function,19 incomplete recovery (34.55％),and 5 (9.09％) remained unchanged after endovascular treatment.Most patients (41/50) began to improve in 3 months after endovascular treatment.The complete recovery ratio between patients encountered improvement of ONP within 30 days and over 30 days had statistical differences (P=0.032).Of 31 patients received complete resolution of ONP at the end of the follow-up,25 (80.65％) fully recovered 6 months after endovascular treatment.Thirty patients (96.77％) fully recovered within one year of endovascular treatment.One (3.23％) received complete resolution of ONP over one year of operation.Within 31 patients encountered complete resolution of ONP,there were 24 patients (77.42％) whose duration of recovery was less than 3 months and 7 patients (22.58％) more than 3 months.Functional recovery was noted firstly in the levator palpebrae muscle,followed by the medial rectus muscle,superior rectus muscle,constrictor muscles of the iris,and ciliary muscle.Patients with incomplete recovery often had residual diplopia in upward gaze and pupillary dysfunction.Conclusions The degrees of oculomotor nerve palsy before endovascular coiling are significantly associated with the paralysis time.Endovascular treatment can promote the recovery of PcomA-induced ONP.The earlier the ONP starting improvement,the better the ONP recoverary after endovascular treatment.The muscles which functional damage occurs early will encounter improvement lately.