Cerebral vasospasm (CVS) is the main complication of spontaneous subarachnoid hemorrhage (SAH), severely affecting clinical outcome of patients with SAH. Apolipoprotein E gene (APOE) is associated with prognosis of spontaneous subarachnoid hemorrhage (SAH), and APOE epsilon 4 allele is reported to be apt to CVS after SAH. The current study aimed to investigate the association of APOE polymorphisms with CVS after SAH. One hundred and eighty-five patients with spontaneous S A H were recruited in the study. APOE genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). CVS was judged by Transcranial Doppler sonography (TCD) combined with patients' condition. chi(2)-test and logistic regression analysis were done by SPSS (version 11.5). The distributions of APOE genotypes and alleles matched Hardy-Weinberg Law. In 185 patients, 21 of 32 (65.7%) patients with APOE epsilon 4 allele showed CVS, which was significantly different from those without APOE 64 allele (56 of 153 patients, 36.6%, P = 0.022). However, neither the presence of epsilon 2 nor epsilon 3 was significantly different from those absent of it (P > 0.05). Logistic regression analysis demonstrated that ApoE epsilon 4 allele was a risk factor (OR = 2.842.95%CI1.072-6.124.P = 0.019) to predispose to CVS after adjusting for age, sex, hypertension or not, hyperlipemia or not, Fisher grade, and Hunt-Hess grade after SAH. Our finding suggests that the patients with APOE epsilon 4 allele predispose to CVS after spontaneous SAH.