Objeetives To investigate the expression patterns of hMSH2 in human bladder transitional cell cercinoma and to assess the correlation of hMSH2 Drotein to tumor cell prolfferation and apoptosiB.Methods We examined the expression patterns of hMSH2 and Ki-67 protein in 101 patients with transitional cell carcinoma (TCC)of the urinary bladder by immunohistochemical technique,futhermore,we also detected apoptosis rate of TCC by in situ end labeling techinque(TUNEL).Results:Urothelium are demostrated uniform expressin of hMSH2,which was restricted to the crypt nuclei.Results Expression was associated with the least differentiated cancer(P ＜0.05).Expression of hMSH2 was significant lyhigher for pT2-4 tumor than pTis-1(P=0.016,＜0.05),The diffirence expression rate of hMSH2 among GI,G2 and G3 of TCC possessed statistics significance(P=0.033,＜0.05),and a difference of statistical significance(P=0.036.＜0.05)also found between G1+G2 and G3 groups of TCC.while we didn't find any relationship between hMSH2 expression and lymphatic invasion(P=0.317).The apoptisis index of the preserved hMSH2 exprssion groups of TCC was higher compared with reduced expression groups (p＜0.01),and the KI-67LI of reduced hMSH2 expression groupWas slighfly lower than the preserved hMSH2 expression groups,which have no statistic significance diference.the AI/KI of reduced hMSH2 expression groups was lower than preserved hMSH2 groups,and statistic significance diferance was found between them.Conclusions Least differentiated and most invasive tumors are mre likely to have reduced hMSH2 expression.which may centribu in the development of a subset of TCCs owning to genetic mutation.hMSH2 germ were related with the automatic apoptosis of TCC,but no statistically significant was found between hMSH2 emutation and the poliferation activity(Ki67 LI).