Objective    To investigate the significance of DNA polymerase iota (Polι) expression in transitional cell carcinoma.     Methods    RT-PCR was applied to detect the expression of Polι in BIU87 and T24 cell lines

and in tissue samples of transitional cell carcinoma from bladder carcinoma and renal pelvic carcinoma.     Results    Expression of Polι was slight in normal bladder mucous membrane but significantly elevated in transitional cell carcinoma cell lines. Compared with Polι  expression in normal bladder mucous membrane

the expression was significantly increased in transitional cell carcinoma tissues (P0.01) and also associated with the grade of transitional cell carcinoma.     Conclusion    The significantly increased expression of polymerase iota may be associated with the genesis and development of transitional cell carcinoma.