OBJECTIVES: I. Compare the bone metastases free and overall survival in patients with asymptomatic recurrent prostate cancer treated with zoledronate vs placebo at different time points. II. Compare the time to first skeletal related events (pathological fractures, surgery to prevent or treat pathological fractures, spinal cord compression, and radiotherapy to bone) and skeletal morbidity rate in patients treated with these 2 regimens. III. Assess quality of life and pain in these patients treated with these 2 regimens.