Non-epithelial non-lymphomatous neoplasms of the gastrointestinal tract are known as stromal tumors (GISTs) because of the tissues in which they originate (4), (16). These neoplasms are rare and account for about 4% of all the tumors of the stomach. Their malignancy and biological and anatomopathological behaviour are related to clinical problems, since their histopathological picture is both complex and controversial. Modern immunohistochemical and ultrastructural (12), (26) studies have identified forms of myogenic or neural origin, which are more differentiated, as well as mixed types with both components, and types, though surely stromal, of uncertain origin, therefore called "uncommitted" (22), (25). The latter are extremely rare and, since it is not yet possible to classify them, some Authors use the term GIST only for these groups. A report of a clinical case of "uncommitted" GIST offers the opportunity to review the literature, highlighting the increased incidence of these tumors (which is probably related partially to the improved diagnostic techniques (3)), their potential malignancy and the difficulty of a correct classification and, therefore, a clear prognosis.