Objective To investigate the inhibitory effects of high mobility group chromosomal protein N2 (HMGN2)on growth of human bladder cancer T24 cells and ectopic tumor growth of nude mice. Methods MTT and flow cytometry assay were conducted to detect cell growth of bladder epithelial cells(T24)cells in vitro. The transplantation tumor models in nude mice were constructed by injecting T24 cells in vivo. The para-tumorswere injected with PBS,HMGN2 protein and cisdichlorodiamineplatinum(DDP),respectively. Tumor volume and weight were calculated. The expression of cell proliferation-related proteins was detected by Western blot assay. Results MTT assay proved that HMGN2 could significantly inhibit the growth of T24 cells. Flow cytometry assay verified that HMGN2 could block T24 cells in S stage of the cell cycle. The average tumor volume and weight in the HMGN2 group and DDP positive control group were smaller than those in the PBS group(P<0.05,respectively), with the tumor inhibitory rate of 25% and 23%,respectively. The results of Westernblot showed that HMGN2 could decrease Bcl-2 expression and increase Bax expression in tumor. Conclusion HMGN2 has a significant antitumor effect on T24 cells and bladder carcinoma in nude mice,which may be associated with the induction of the apoptosis of carcinoma cells and the regulation of the cell cycle.