We report a case of diffuse gastric metastasis from lobular carcinoma of the breast arising in a 65-year-old woman. The patient had undergone mastectomy 5 years ago and on her last admission she had complaints of epigastric discomfort and weight loss. Computed tomography scan showed diffuse gastric wall thickening. Gastric biopsy revealed metastatic lobular carcinoma and the patient underwent a total gastrectomy. Histologic examination demonstrated transmural neoplastic infiltration with uniform tumor cells which were arranged in rows and single cells. Diagnostic difficulties and histopathologic features of this rare entity were discussed.