We conducted a systematic review and meta-analysis of mechanical thrombectomy in the treatment of ischemic stroke and assessed factors for technical and clinical success and survival. We searched the literature using MEDLINE and EMBASE for January 1, 2000, through March 1, 2006. Studies were limited to those in human beings; there were no language or study design restrictions. Validity assessment was performed using the Newcastle-Ottawa Scale. The pooled cohort was compared with a historical cohort matched for sex, age, and National Institutes of Health Stroke Survey score. The search yielded 114 publications. Two authors determined inclusibility (interrater agreement, kappa = 0.94). Mean preprocedure National Institutes of Health Stroke Survey score was 20.4. The middle cerebral artery (36%) and the posterior circulation (38%) were the most frequently occluded areas. The clot was accessible in 85% of the patients. Hemorrhage occurred in 22% of the patients. Of 81 patients with concurrent thrombolysis, 18.5% had hemorrhage compared with 27.3% of 66 patients without thrombolysis (P = .21). Of the 126 patients with accessible clots, 36% had a good modified Rankin score (<or=2) and 29% died; in patients with inaccessible clots, 24% had a good modified Rankin score and 38% died. Factors associated with clinical success were younger age (P = .001) and lower National Institutes of Health Stroke Survey score at admission to the hospital (P = .001). Compared with a matched cohort, patients who received mechanical intervention were 14.8 times more likely to have a good modified Rankin score (95% confidence interval, 4.4-50.0; P < .001). Percutaneous mechanical embolectomy in the treatment of acute ischemic stroke is feasible and seems to provide an option for some patients seen after the interval for administration of intravenous tissue plasminogen activator therapy has elapsed.