CONTEXT: Observational studies suggest that heavy alcohol consumption may increase the risk of stroke while moderate consumption may decrease the risk. OBJECTIVE: To examine the association between alcohol consumption and relative risk of stroke. DATA SOURCES: Studies published in English-language journals were retrieved by searching MEDLINE (1966–April 2002) using Medical Subject Headings alcohol drinking, ethanol, cerebrovascular accident, cerebrovascular disorders, and intracranial embolism and thrombosis and the key word stroke; Dissertation Abstracts Online using the keywords stroke and alcohol; and bibliographies of retrieved articles. STUDY SELECTION: From 122 relevant retrieved reports, 35 observational studies (cohort or case control) in which total stroke, ischemic stroke, or hemorrhagic (intracerebral or total) stroke was an end point; the relative risk or relative odds and their variance (or data to calculate them) of stroke associated with alcohol consumption were reported; alcohol consumption was quantified; and abstainers served as the reference group. DATA EXTRACTION: Information on study design, participant characteristics, level of alcohol consumption, stroke outcome, control for potential confounding factors, and risk estimates was abstracted independently by 3 investigators using a standardized protocol. DATA SYNTHESIS: A random-effects model and meta-regression analysis were used to pool data from individual studies. Compared with abstainers, consumption of more than 60 g of alcohol per day was associated with an increased relative risk of total stroke, 1.64 (95% confidence interval CI, 1.39-1.93); ischemic stroke, 1.69 (95% CI, 1.34-2.15); and hemorrhagic stroke, 2.18 (95% CI, 1.48-3.20), while consumption of less than 12 g/d was associated with a reduced relative risk of total stroke, 0.83 (95%, CI, 0.75-0.91) and ischemic stroke, 0.80 (95% CI, 0.67-0.96), and consumption of 12 to 24 g/d was associated with a reduced relative risk of ischemic stroke, 0.72 (95%, CI, 0.57-0.91). The meta-regression analysis revealed a significant nonlinear relationship between alcohol consumption and total and ischemic stroke and a linear relationship between alcohol consumption and hemorrhagic stroke. CONCLUSIONS: These results indicate that heavy alcohol consumption increases the relative risk of stroke while light or moderate alcohol consumption may be protective against total and ischemic stroke.