ALTHOUGH from a clinical viewpoint mesenchymal tumors of the stomach are often considered rare, they actually constitute a significant percentage of gastric neoplasms and frequently present a real challenge in differential diagnosis and treatment. Because there is usually little to distinguish these tumors in their clinical behavior from epithelial neoplasms, the diagnosis is seldom made until the specimen is examined in the pathologic laboratory. This discussion deals with a general consideration of the problem and a review of the cases of mesenchymal tumors of the stomach encountered at the Detroit Receiving Hospital during the past twenty-six years. CLASSIFICATION Included in the group of mesenchymal tumors are all neoplasms arising from the various components of the gastric wall, exclusive of the surface lining, especially the glands, i. e., tumors arising from muscle, connective tissue, fat, nerve, blood vessels and lymphoid tissue. Many classifications have been proposed for gastric neoplasms based on