To explore the expression of cancerous inhibitor of PP2A (CIP2A) and evaluate its role in bladder cancer.RT-PCR was used to detect the expression of CIP2A mRNA from 38 cases of patients with bladder cancer and 12 cases of normal bladder tissue. The CIP2A protein expression levels in 99 cases of patients with bladder cancer and 12 cases of normal tissue was detected by immunohistochemical staining . And the serum contents of CIP2A protein of 38 patients with bladder cancer and 40 normal controls were detected by ELISA.The expression of CIP2A mRNA was detected in 29/38 cases (76.32%) of bladder cancer. And there was no expression in normal tissue (P < 0.05). The positive rate of CIP2A protein was 63.64% in 99 cases of bladder cancer tissues and no expression detected in normal tissues(P < 0.05). ELISA results showed that the serum content of CIP2A in patients with bladder cancer was significantly higher than that in normal controls (median:0.015 2 vs 0.001 8 ng/L, P < 0.05).The tissue and serum expressions of CIP2A in patients with bladder cancer are higher than those in normal controls. And CIP2A may be used as an indicator of the biological behavior of bladder cancer.