Long non-coding RNAs (lncRNAs) have been shown to have important regulatory roles in cancer biology, and lncRNA H19 is essential for human tumor growth. However, little is known about how abnormal expression of H19 contributes to bladder cancer cell proliferation. In the study, we first evaluated the expression of H19 in bladder cancer tissues by real-time PCR, and defined the biological functions. We found that H19 expression levels were remarkably increased in bladder cancer tissues compared with adjacent normal control, and forced expression of H19 promoted bladder cancer cell proliferation in vitro. Inhibitor of DNA binding/differentiation 2 (ID2) expression levels were upregulated in bladder cancer tissues and in bladder cancer cells. A significant positive correlation was observed between H19 levels and ID2 levels in vivo. We further demonstrated that overexpression of H19 resulted in significant increase in the expression of ID2, whereas H19-knockdown decreased ID2 expression in vitro. Gain-of-function and loss-of-function studies demonstrated that upregulated H19 increased bladder cancer cell proliferation by increasing ID2 expression. Conclusions: Upregulated H19 increases bladder cancer growth by regulating ID2 expression, and thus may be helpful in the development of effective treatment strategies against bladder cancer. © 2013 The Authors Journal compilation © 2013 FEBS.