A solitary primary gastric plasmacytoma in a 76-year-old man is reported. Presenting symptoms were anorexia, progressive weakness, and weight loss. Laboratory findings included anemia (Hgb 10.3 g/100 ml), trace-positive stool guaiac, and hyperglobulinemia of 3.3 g/100 ml with a diffuse increase in beta globulins (22%). Serum M protein, Bence-Jones proteinria, and multiple myeloma were absent. The patient was treated by chemotherapy alone with clinical improvement but died 6 months later from an unrelated stroke. The clinicopathologic features of gastric plasmacytoma are discussed.