A randomized, double-blind, placebo-controlled multicenter trial involving 107 men receiving bicalutamide ('Casodex') 150 mg/day therapy following radical therapy for prostate cancer assessed tamoxifen ('Nolvadex') 20 mg/day and anastrozole ('Arimidex') 1 mg/day for the prophylaxis and treatment of gynecomastia/breast pain. Tamoxifen, but not anastrozole, significantly reduced the incidence of gynecomastia/breast pain when used prophylactically and therapeutically. Serum testosterone levels increased with tamoxifen relative to placebo but prostate-specific antigen levels declined in all treatment groups. Further studies are needed to define the optimum tamoxifen dose and to assess any impact on cancer control. The use of tamoxifen in this setting remains to be investigated.