Abstract: Purpose: The aim of this prospective study was to compare the efficacy and toxicities of gemcitabine to cisplatin as a radio sensitizer in trimodality treatment of bladder transitional cell carcinoma. Methods: It was a prospective study on100 patients with bladder TCC, clinical stage T2 or T3 N0 M0 who underwent concurrent radio chemotherapy after maximum safe trans-urethral resection. Patients were divided into 2 groups: gemcitabine group, received weekly doses of gemcitabine 125mg/m2 , and cisplatin group, received weekly doses of cisplatin 40mg/m2 concurrently with 66 Gy of conventional radiation therapy. Results: Disease free survival in gemcitabine group was 79.4%, while in cisplatin group was 77.6% with insignificant differences. All patients in cisplatin group tolerated treatment protocol completely, while six patients in gemcitabine group could not completed their weekly gemcitabine doses because of grade III gastrointestinal toxicity. Conclusions: Gemcitabine is a reasonable option in trimodality treatments in urinary bladder preservative strategies. [