['To determine the efficacy and safety of a high-dose-rate (HDR) brachytherapy schedule in the treatment of bladder cancer and to investigate the impact of different values of repair half-times and alpha/beta ratios on the design of the HDR schedule.', 'Between 2000 and 2002, 40 patients with T1G3 and T2 bladder carcinoma were treated with 30 Gy external beam radiotherapy followed by interstitial HDR brachytherapy to a total dose of 32 Gy in 10 sessions of 3.2-Gy fractions in two fractions daily with a 6-h interfraction interval. The local control rate and toxicity were compared with a historical group of 108 patients treated with 30 Gy external beam radiotherapy followed by 40-Gy interstitial low-dose-rate (LDR) brachytherapy. The HDR schedule was designed to be biologically equivalent to the previously used LDR schedule with the linear-quadratic model, including incomplete mono-exponential repair.', 'The local control rate at 2 years was 72% for HDR vs. 88% for LDR brachytherapy (p = 0.04). In the HDR group, 5 of 30 evaluable patients encountered serious late toxicity: 4 patients developed a contracted bladder with inadequate capacity (<100 mL), and 1 patient required cystectomy because of a painful ulcer at the implant site. In the LDR group, only 2 of 84 assessable patients developed serious late toxicity. One patient developed a persisting vesicocutaneous fistula and the other a urethral stricture due to fibrosis. The difference in observed late toxicity for HDR vs. LDR was statistically significant (p = 0.005). The increased late toxicity with the HDR schedule compared with the LDR schedule suggests a short repair half-time of 0.5-1 h for late-responding normal bladder tissue.'] Is low-dose-rate brachytherapy superior to high-dose-rate brachytherapy for bladder cancer?