Objective:To investigate the differential expression of VEGF165b in the transitional cell carcinoma of the bladder (TCCB) and normal bladder tissues and its role in the development of TCCB. Methods: S-P immunohistochemistry was used to detect the expression of VEGF165b protein in 38 specimens of paraffin-embedded TCCB tissues and 36 specimens of paraffin-embedded normal bladder tissues. RT-PCR was performed to detect the expression of VEGF165b mRNA in 55 specimens of fresh TCCB tissues and 43 specimens of fresh normal bladder tissues. Results: Among 36 of normal bladder tissues

35 specimens had positive expression of VEGF165b protein

with the positive rate of 97.22% (35/36) that was significantly higher than 21.05% (8/38) (P<0.05) in TCCB tissues (P<0.05). The positive rate of VEGF165b mRNA in normal bladder tissues was 95.35%(41/43)

while that of TCCB tissues was only 18.18%(10/55). The positive expression rate of VEGF165b mRNA in normal bladder tissues was significantly higher than that in TCCB tissues(P<0.05). The expression of VEGF165b was significantly related to clinical stage and pathological grade in TCCB tissues(P<0.05). Conclusions: VEGF165b might play a rolein inhibiting development of TCCB.