Objective To evaluate the relationship between Chlamydia pneumoniae(CP) infection and lung cancer.Methods literatures that reported on the associations between CP and lung cancer were retrieved by searching international and national databases.Meta-analysis was done by RevMan 4.2 software.The pooled OR values and 95% CI were calculated,and published bias was assessed by funnel plots.Results Totally 10 studies with 1 769 cases and 1 922 controls were enrolled.The analysis showed that the pooled OR of the association between chronic CP infection and lung cancer was 2.17 with the 95% CI of 1.43 to 3.28.Conclusion CP infection may be associated with lung cancer.CP infection may be a potential risk factor for lung cancer.