We report an unusual case of osteoblastic metastasis from gastric carcinoma. In this case, bone metastasis was the initial manifestation of the cancer. The laboratory findings revealed mild hypocalcemia and markedly elevated alkaline phosphatase levels. Plain X-ray showed mottled osteoblastic changes in the pelvis. Bone marrow and bone biopsy of the pelvis revealed metastatic adenocarcinoma with increased osteoblastic activity. An extensive search for the primary site revealed advanced gastric carcinoma, which was confirmed by endoscopic biopsy.