This study examined the differences in tumor formation of three bladder tumor cell lines (BIU-87,T24 and E J) after subcutaneously transplanted into nude mice,in order to find the best technique for establishing in vivo bladder tumor model.BIU-87,T24 and EJ cells at logarithmic phase were re-suspended in serum-free medium.The cells suspensions of the identical concentration were subcutaneously transplanted into nude mice and then the success rate and tumor growth were compared among the three cell groups.The results of tumor formation were pathologically evaluated.Lung,liver and kidney tissues were also pathologically examined for distant metastasis.The proliferation of the three cells were determined by immunohistochemically detecting the PCNA expression in the tumors.The results showed that the success rates of EJ and T24 cells were significantly higher than that of BIU-87 cells and no distant metastasis was noted among the three groups.The proliferation levels of EJ and T24 cells was significantly higher than that of BIU-87.But at the later stage of tumor formation,as compared with T24 cells,EJ grew more vigorously,soon resulting in the central necrosis of tumor,which affected the measurement of the actual size of the tumors.Moreover,PCNA staining exhibited that the proliferation of EJ and T24 was significantly higher than that of BIU-87 cells.It is concluded that as compared with BIU-87 cells,EJ and T24 cells had higher success rates,with not significant differences in death rate and distant metastasis found among them.There existed no significant difference in tumor formation between EJ and T24 cells and T24 cells do not rupture easily,which makes it a better cell line for the establishment of in vivo bladder tumor model.