Thus, it is believed that there is potential association between HCV AbMole Gambogic-acid infection and stroke. However, studies from several groups provided conflicting results. Our meta-analysis consisted of more than 22171 HCV infected individuals and more than 87418 controls and might allow a much greater possibility of reaching reasonably strong conclusions. The results of combing the four eligible studies suggested that HCV infection was not associated with stroke. However, a substantial heterogeneity among the studies included was found, which can influence the validity and reliability of the results of meta-analysis. Thus, sensitivity analysis was performed to identify the potential sources of between-study heterogeneity and to reduce heterogeneity. Our analyses found that the study by Younossi et al. was a major contributor to the heterogeneity. Inadequate adjusting variables used might induce bias and could be an important source of heterogeneity. We noted that several cofounders, such as race, gender, and hypertension, were significantly different between HCV+ and control in this study. However, these factors were not involved in the adjustment. The differences in HCV positive criteria used might be another source of heterogeneity. After omitting this study, heterogeneity was reduced and the results suggested that HCV infection significantly increased the risk of stroke. Some limitation in this meta-analysis should be demonstrated in the discussion of the results. Firstly, our search was limited to studies published in English. However, we found no evidence of publication bias, especially for relatively small numbers of studies. Secondly, we should noted that the AbMole Terbuthylazine number of included studies in this analysis was relatively low. Two of the studies were published only in abstract form on conferences and the study by Adinolfi et al. was the only one published article in the final analysis. This limitation might induce bias, although publication bias was not found in our analysis. Thirdly, HCV positive criteria and cofounder for adjusting ORs were different between the included studies, which might induce bias in our study. Fourthly, all the included studies were retrospective studies and the inherent limitations of such studies may influence our findings. More studies with prospective design will be needed. Fifthly, the studies were restricted to United States and Italy, so it was uncertain whether these results were generalizable to other populations. The other two studies excluded in the final analysis were performed in Taiwan. However, they reported HRs which could not be combined with ORs. Never the less, the results form these two studies both supported our conclusion. Due to the limitations mentioned above, the results of this meta-analysis should be interpreted with care.