Bone metastases diffusely invading the bone marrow from gastric cancer often manifest a rapid clinical course and the prognosis is very poor due to hematologic disorders such as DIC (disseminated intravascular coagulation) and/or MAHA (microangiopathic hemolytic anemia). The objective of this study was to clarify the clinicopathological features and prognosis of patients with gastric cancer in whom diffuse bone metastasis associated with hematologic disorders were evident. Thirty-eight patients with bone metastasis from a primary gastric cancer were thus selected and placed into 2 groups consisting of 15 with diffuse bone metastasis with DIC and/or MAHA, and 23 patients who had bone metastasis without hematological disorders. We compared the clinicopathological features and prognosis between the two groups. The clinicopathological features in patients with diffuse bone metastasis accompanied by hematologic disorders were significantly related to undifferentiated adenocarcinoma, a relatively younger age, elevated levels of serum ALP-BI and LDH, and a lower frequency of extraosseous metastasis. The median survival time after manifestation was 2 and 11 months for the patients with or without hematologic disorders, respectively. The prognosis was significantly worse in cases of DIC with the median survival being only one month. Since, prognosis of diffuse bone metastasis from gastric cancer is significantly poor, close attention should be directed to the specific clinicopathologic features related to diffuse bone metastasis plus hematologic disorders. Regarding high risk patients, a regular follow-up of the serum chemistry levels and a bone scan will aid in the early detection of the disease.