We evaluated the effects of bisphosphonate (BP) treatment in five patients with hormone-refractory prostate cancer (HRPC), experiencing bone pain from metastases to the bone, and assessed changes in serum prostate specific antigen (PSA) levels, bone pain, and quality of life (QOL). Treatment with incadronate disodium (10 mg) in saline was administered at 2-week intervals for a total of 6 times. Evaluation of the treatment included the incidence of adverse events, QOL, bone pain, pain scale, and blood analyses including tumor markers. BP treatment was generally well tolerated by all five patients. The effects of BP treatment on serum PSA values were evaluated as prominent response (PR), no change (NC) and progressive disease (PD) in one, two and two cases of PD, respectively. During BP treatment, serum type I procollagen values decreased in patients, but there was no large change in serum type I collagen values. Only one patient experienced increased pain; pain was well controlled in the others. The QOL evaluation by Short-Form 36 (SF-36), showed no change in scores during BP treatment except for general health. These results suggested that BP treatment is safe and feasible. It may be effective for the treatment of those HRPC patients with bone pain and may become one of the choices for treatment of HRPC.