【Objective】 To investigate the expression of negative costimulatory molecule PD-L1 in non-muscle invasive bladder cancer (NMIBC) and its effect on intravesical instillation therapy after surgery. 【Methods】 10 normal bladder tissues and 131 bladder cancer tissues were available from patients underwent TUR-Bt at our institution between January 2006 and March 2013. NMIBC patients were administrated with epirubicin or Picibanil for adjuvant intravesical instillation therapy. Immunohistochemistry staining was used to detect the PD-L1 expression in tumor and normal specimens. All data of the time and number of tumor recurrence and progression were recorded. 【Results】 PD-L1 expression were negative in normal bladder 0(0/10)

comparing with 56.5%(74/131)in NMIBC (P = 0.000) . The expression of PD-L1 in pTa and pT1 bladder cancer were 35.14%(13/37)and 60.64%(57/94)

respectively (P = 0.008). The tumor recurrence and progression rates in PD-L1(+) patients were 37.8% and 10.8%

which were higher than 12.3% and 3.5% in PD-L1(-) patients(P 0.05). 【Conclusions】 Expression of negative costimulatory molecule PD-L1 in NMIBC is significantly correlated with pathologic stage and prognosis. Detecting the PD-L1 might help determine the optimal instillation agents for NMIBC patients.