Circular RNAs (circRNAs) have spurred considerable interest in numerous tumors. We aimed to investigate the clinical, prognostic, and diagnostic roles of circRNAs in human lung cancer. We systematically searched PubMed, Web of Science, EMBASE, Scopus, CBM, and the Cochrane Library databases up to July 24, 2018. Eligible studies about the relationship between circRNAs expression and clinical, prognostic, and diagnostic outcomes in patients with lung cancer were in our study. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were to investigate clinical parameters, and hazard ratios (HRs) and 95% CIs to estimate overall survival (OS). A total of 23 relevant studies were eligible, with 15 on clinicopathological features, 14 on prognosis, and six on diagnosis. For clinical features, high expression of oncogenic circRNAs was remarkably related to poor clinical parameters. Whereas, the results of tumor-suppressor circRNAs were the complete opposite. For the prognostic roles, oncogenic circRNAs had an unfavorable impact on overall survival (OS: HR = 3.24, 95% Cl: 2.70-3.77), and elevated level of tumor-suppressor circRNAs was correlated with longer survival (OS: HR = 0.57, 95% Cl: 0.43-0.70). For the diagnostic values, the pooled result showed an area under the curve (AUC) of 0.86, with 77% sensitivity and 81% specificity in distinguishing patients with lung cancer from healthy ones. The above results suggested that circRNAs have the potential to be novel indicators for prognostic and diagnostic evaluation of patients with lung cancer.