X-ray findings of bone metastatic lesions from 81 cases of stage D2 prostatic cancer were examined before and following endocrine therapy. Untreated lesions were classified into five types; osteoblastic (15%), mixed, but mainly osteoblastic (31%), mixed, but mainly osteolytic (17%), osteolytic (10%), and undetermined with a positive bone scan (27%). Patients with two mixed types had a tendency of widely speeded areas of metastasis and elevated serum prostatic acid phosphatase. Temporal enlargement of sclerotic lesion immediately after the start of therapy did not indicate disease progression. In many cases, changes from osteolytic to osteoblastic patterns were noticed in the same lesion regardless of the effects of endocrine therapy. Remodeling to the sclerotic pattern appeared as curative changes. From these findings, it was concluded that the natural course of bone lesions showed a tendency to change from the osteolytic to osteoblastic type and relapse was often accompanied by an increase of the osteolytic type lesion. Evaluation of therapeutic effects based on remodeling, changes in number and areas of lesions, and the appearance of new lesion correlated well with prognosis.