200 patients that are candidates for intravesical BCG therapy and 20 control patients with no history of malignancy will be enrolled. The study group wol;; be asked to provide a urine sample just prior to receiving their first BCG treatment(week # 1) and just prior to receiving their last (week # 6) BCG treatment. The control patients will provide one urine sample only. Samples will be analysed by enzyme-linked immunosorbant assay(ELISA). clinical data will be reviewed on tumor stage and grade prior to BCG, timme to recurrence, tumor stage and grade of recurrence, time to disease progression and death, cause of death and total follow-up time.