MicroRNA-16 (miR-16) has been demonstrated to regulate proliferation and apoptosis in many types ofcancers, but its biological function in bladder cancer remains unknown. Here, we found expression of miR-16 tobe downregulated in bladder cancer in comparison with the adjacent normal tissues. Enforced expression of miR-16 was able to inhibit cell proliferation in TCHu-1 cells, in line with results for miR-16 antisense oligonucleotides(antisense miR-16). At the molecular level, our results further revealed that cyclin D1 expression was negativelyregulated by miR-16. Therefore, the data reported here demonstrate that miR-16 is an important regulator inbladder cancer, which will contribute to better understanding of important mis-regulated miRNAs.