Nuclear venogram of the lower extremity using Tc-99m labeled RBCs was performed in a 62-year-old man with prostate cancer, and suggested active bleeding in the left descending colon and sigmoid. However, the patient had a follow-up bone scan using Tc-99m MDP, which revealed markedly increasing diffuse radioactivity in the left pelvic bone, indicating progressive metastasis. Increasing osteoblastic lesion involving the entire left iliac bone was also found on follow-up CT scan of the pelvis. The patient's low hemoglobin and hematocrit levels were stabilized after transfusion with one pint of blood. However, the patient died 6 months later because of disseminated metastases.