OBJECTIVE : To evaluate the anti-cancer effect of unmethylated cytosine-phosphorothioate-guanine (CpG)-containing oligodeoxynucleotides (ODNs) on human bladder cancer UM-UC-3 cells, our study was carried out. METHODS : The viability of cells (UM-UC-3, T24 and SV-HUC-1) with CpG ODN treatments was examined by cell counting kit-8 (CCK-8) assay. Apoptosis and cell cycle phase were determined by flow cytometry analysis. Pre-apoptosis factors of caspase-3, p53, B-cell lymphoma 2 associated X protein (Bax) and anti-apoptosis factor of B-cell lymphoma 2 (Bcl-2) were detected by western blot. RESULTS : Experimental results showed that the viability of human bladder cancer cells (UM-UC-3 and T24) with CpG ODN treatment was decreased and the viability of human normal urothelial cells (SV-HUC-1) with CpG ODN treatment was increased with time-dependance manner. Moreover, CpG ODN increased the apoptosis rate of UM-UC-3 cells and arrested more cells in G0G1 phase. Furthermore, the expression of caspase-3, p53 and Bax were increased and the expression of Bcl-2 was decreased with CpG ODN treatment on UM-UC-3 cells. CONCLUSIONS : CpG ODN promoted the proliferation of normal urinary transitional epithelial cells (SV-HUC-1) and inhibited the cell viability of human bladder cancer cells (UM-UC-3 and T24) in vitro. CpG ODN induced the apoptosis of human bladder cancer (UM-UC-3) cells in a cascade progress via enhancing the expression of caspase-3, p53 and Bax, and inhibiting the expression of Bcl-2 with significant time-dependancy. CpG ODN inhibited cell cycle distribution of human bladder cancer (UM-UC-3) cells with more cells were arrested in G0G1 phase. This study suggested that the CpG ODN is the potential candidate on human bladder cancer.