To evaluate the relationship between the expression of cathepsin D(CD)and biological be haviour of bladder transitional cell carcinoma (BTCC)and the mechanisms of invasiveness. Methods The expression of CD and BFGF was detected by standard ABC immunohistochemical technique in 33 paraffin embedded tissue speci mens of BTCC. Results All normal transitional ceils were weakly stained. The over expression rate of CD in BTCC group was significantly higher than in normal control group (P< 0. 05). Fisher's accurate analysis showed that over expression rate of CD in turnout cells closely correlated with different pathological grades(P~0. 05), clinical stages (P<0. 05),number of lesions(P<0. 05)and postoperative receurance(P