BACKGROUND: The safety and efficacy of reconstructive and deconstructive endovascular treatments of very large/giant intracranial aneurysms are not completely clear. PURPOSE: Our aim was to compare treatment-related outcomes between these 2 techniques. DATA SOURCES: A systematic search of 3 data bases was performed for studies published from 1990 to 2017. STUDY SELECTION: We selected series of reconstructive and deconstructive treatments with =10 patients. DATA ANALYSIS: Random-effects meta-analysis was used to analyze occlusion rates, complications, and neurologic outcomes. DATA SYNTHESIS: Thirty-nine studies evaluating 894 very large/giant aneurysms were included. Long-term occlusion of unruptured aneurysms was 71% and 93% after reconstructive and deconstructive treatments, respectively (P = .003). Among unruptured aneurysms, complications were lower after parent artery occlusion (16% versus 30%, P = .05), whereas among ruptured lesions, complications were lower after reconstructive techniques (34% versus 38%). Parent artery occlusion in the posterior circulation had higher complications compared with in the anterior circulation (36% versus 15%, P = .001). Overall, coiling yielded lower complication and occlusion rates compared with flow diverters and stent-assisted coiling. Complication rates of flow diversion were lower in the anterior circulation (17% versus 41%, P<.01). Among unruptured lesions, early aneurysm rupture (within 30 days) was slightly higher after reconstructive treatment (5% versus 0%, P = .08) and after flow diversion alone compared with flow diversion plus coiling (7% versus 0%). LIMITATIONS: Limitations were selection and publication biases. CONCLUSIONS: Parent artery occlusion allowed high rates of occlusion with an acceptable rate of complications for unruptured, anterior circulation aneurysms. Coiling should be preferred for posterior circulation and ruptured lesions, whereas flow diversion is relatively safe and effective for unruptured anterior circulation aneurysms.