Abstract: Objective :To investigate the transcription level and clinical significance of tumor as-sociated antigen MUC1 and its isoform MUC1/Y in human bladder cancer. Methods :The expression ofMUC1 and its isoform MUC1/Y mRNA was examined by RT-PCR in 22 cases of bladder cancer and10 normal bladder tissues. Results :The mRNA expression level of MUC1 and its isoform MUC1/Y inbladder cancer tissues was significantly higher than that in normal bladder tissues (P<0.01). Meanwhile,the expression level of MUC1/Y mRNA in bladder cancer tissues of stages Ⅲ-Ⅳ was significantlyhigher than that of tissues of stages Ⅰ-Ⅱ (P<0.01). Conclusion :Detecting transcription levels ofMUC1 and its isoform MUC1/Y may be helpful in the diagnosis and immunotherapy of bladder cancer,and it can predict metastasis and invasion.