Objective To investigate the role of early cerebral blood flow (CBF) measurement in predicting the prognosis of patients with delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH).Methods A total of 150 patients with DCI after SAH who were treated in our hospital from January 2008 to November 2012 were enrolled, and according to the clinical outcome at 5 years after surgery, these patients were divided into survival group with 96 patients and death group with 54 patients. Clinical features were compared between the two groups. The receiver operating characteristic (ROC) curve was plotted, and the area under the curve was calculated to evaluate the predictive efficiency of related parameters. Univariate and multivariate Cox regression analyses were used to identify the risk factors for the prognosis of patients with DCI after SAH. The Kaplan-Meier method was used to plot cumulative survival curves, and the log-rank test was used for the comparison of survival rates.Results Among these 150 patients, 96 (64%) survived and 54 (36%) died at 5 years after surgery. The univariate and multivariate Cox regression analyses showed that CBF <15.82 ml/100g/min, PAASH grade ≥ 4, and Fisher grade ≥ Ⅲ were risk factors for the prognosis of the patients (P<0.05). After 5 years of follow-up, the patients with a CBF of <15.82 ml/100g/min had a significantly lower cumulative survival rate than those with a CBF of ≥ 15.82 ml/100g/min[18% (9/50) vs 45% (45/100), P<0.05].Conclusions CBF on admission can be used as an important indicator for predicting the prognosis of patients with DCI after SAH.