Objectives. To investigate the efficacy and tolerability of bicalutamide (Casodex) as immediate therapy, either alone or as adjuvant to treatment of curative intent, in patients with localized or locally advanced (T1b-T4, any nodal status, M0) prostate cancer. Methods. This was a multicenter, prospective, randomized, double-blind, placebo-controlled trial in Europe, South Africa, Australia, and Mexico and is part of the Casodex Early Prostate Cancer program. Results. A total of 3603 men were randomized to receive bicalutamide (n = 1798) or placebo (n = 1805). The patient demographics were well balanced between the two groups. Prior therapy of curative intent had been given to 64% of the patients (prostatectomy [44%], radiotherapy [18%], and prostatectomy and radiotherapy [2%]) and 36% had been monitored with watchful waiting. After a median follow-up of 2.6 years and a median exposure to the study drug of 2.2 years, a significant 43% reduction in the risk of objective progression was observed for the bicalutamide group compared with the placebo group (hazard ratio 0.57, 95% confidence interval 0.48 to 0.69, P ≪0.0001). The time to prostate-specific antigen doubling was significantly delayed for the bicalutamide group compared with the placebo group (hazard ratio 0.37, 95% confidence interval 0.32 to 0.43, P ≪0.001). The survival data were immature, with 7.2% overall mortality. The most frequently reported adverse events with bicalutamide were gynecomastia alone (17.4%), breast pain alone (17.6%), and gynecomastia with breast pain (47.5%). Conclusions. Bicalutamide 150 mg daily as immediate therapy, alone or as adjuvant to treatment of curative intent, significantly reduced the risk of disease progression in patients with localized or locally advanced prostate cancer. Longer follow-up is underway to assess any benefit in overall survival.