Background: Bladder cancer is a common cancer of urinary system, with high incidence and mortality. LncRNA CASC2 as a tumor suppressor has been reported to be involved in many human tumors. In this study, we aimed to explore the diagnostic value of CASC2 for bladder cancer patients.Methods: qRT-PCR was used to detect the expression level of CASC2 in 140 bladder cancer patients and 90 healthy volunteers. The differences of CASC2 expression between the cancer group and healthy group were analyzed using student’s t test. The correlation of CASC2 expression with clinical characteristics of the bladder cancer patients was estimated with Chi-square test. In addition, ROC curve was plotted to evaluate the diagnostic value of CASC2 for bladder cancer patients.Results: Serum CASC2 level was lower in bladder cancer patients than that in healthy group (P<0.05). The expression level of CASC2 was significantly associated with histological grade (P=0.000), TNM stage (P=0.000), and lymph node metastasis (P=0.001). The area under the ROC curve (AUC) was 0.864 and the optimal cutoff value was 0.955, suggesting the diagnostic value of CASC2 for bladder cancer. The diagnostic sensitivity was 77.8% and specificity was 85.7%.Conclusion: CASC2 may be a novel biomarker for early diagnosis of bladder cancer.