BACKGROUND AND OBJECTIVE: Early recanalization of acute posterior circulation stroke caused by large intracranial vessel occlusion by mechanical thrombectomy with stent retrievers may improve the outcome of patients. However, evidence of patient selection is still lacking. This study investigated the prognostic factors of acute posterior circulation stroke caused by large intracranial arterial occlusion when treated with stent-retriever thrombectomy. METHODS: A total of 69 patients from March 2012 to November 2016 were included in the study. These patients presented with acute posterior circulation stroke caused by large intracranial vessel occlusion and underwent mechanical thrombectomy with Solitaire AB or combined with additional balloon and/or stenting angioplasty. Baseline characteristics, clinical course, and imaging data of the patients were analyzed. Good clinical outcome (defined as a modified Rankin Scale score of 0-2 at 90 days) and safety outcome (defined as death within 90 days after thrombectomy) were considered as end points. The association between factors with good clinical outcome and safety outcome was evaluated with both logistic regression and receiver operating characteristic curve analyses. RESULTS: Of the 69 patients, mean age was 59 years (standard deviation, 8 years) and men comprised 82.6% (57/69). The median onset-to-treatment time was 360 minutes (interquartile range, 250-537 minutes). The median National Institutes of Health Stroke Scale (NIHSS) score was 25 (interquartile range, 17-30) on admission. Successful recanalization was achieved in 62 of the 69 cases (89.9%) and 36.2% (25/69) were independent at 90 days. Regression analysis showed that stroke subtype (intracranial atherosclerotic disease vs. embolism; odds ratio [OR], 0.101; 95% confidence interval [CI], 0.020-0.501; P = 0.005), baseline NIHSS score (>= 22 vs. <22; OR, 0.157; 95% CI, 0.040-0.614; P = 0.008) and posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS) on diffusion-weighted imaging [DWI] (weighted magnetic resonance imaging) before thrombectomy (>= 6 vs. <6; OR, 7.335; 95% CI, 1.495-36.191; P = 0.014) were independent predictive factors of good clinical outcome, respectively at 90 days, whereas high NIHSS score (>= 30 vs. < 30; OR, 5.569; 95% CI, 1.573-19.716; P = 0.008) and collateral status (>= 2 vs. <2; OR, 0.210; 95% CI, 0.059-0.752; P = 0.016) before treatment were associated with mortality at 90 days. Based on receiver operating characteristic curves, baseline NIHSS score (area under the curve [AUC] = 0.779; cutoff, >= 22; P < 0.001; sensitivity, 72%; specificity, 77.3%), pc-ASPECTS on DWI (AUC = 0.820; cutoff, >= 6; P < 0.001; sensitivity, 72%; specificity, 77.3%) before treatment were independent indicators predicting good clinical outcome at 90 days. Increased risk of death by 90 days was associated with baseline NIHSS score (AUC = 0.719; cutoff, >= 30; P = 0.007; sensitivity, 64.7%; specificity, 78.9%) and worse collateral status (AUC = 0.820; cutoff, >= 2; P < 0.001; sensitivity, 58.8%; specificity, 80.8%) before treatment. CONCLUSIONS: Stroke subtype, initial stroke severity, and pc-ASPECTS on DWI as well as collateral status before thrombectomy are independent factors affecting the clinical outcome in patients treated with Solitaire AB thrombectomy for acute posterior circulation stroke caused by large intracranial vessel occlusion.