Gastrointestinal mesenchymal tumors have been classified as benign (leiomyoma) or malignant (leiomyosarcomas). More recently, these tumors have been termed gastrointestinal stromal tumors (GISTs). GISTs have a highly variable clinical course. This review analyzes the clinical presentation, pathologic examination, and long-term follow-up of patients with GIST. A retrospective analysis of the clinical course of patients with GIST at a single institution from 1986 to 1998 was performed. Nineteen patients with GIST (12 gastric, two duodenal, three jejunal, and two rectal) were treated. The most common clinical presentation was gastrointestinal bleed. CT scans, contrast studies, and endoscopy were used to identify a tumor mass. Diagnosis of GIST was made in only two patients preoperatively. Tumor size ranged from 0.8 to 23 cm. Histology of the tumors was variable. All patients underwent surgical resection with curative intent. Follow-up ranged from 2 to 55 months. There were two perioperative deaths. Local recurrence occurred in one patient. GISTs are uncommon. Preoperative diagnosis can be difficult, and often the diagnosis is made at the time of surgery. With complete resection of the tumor the clinical course is favorable with very few local recurrences. Therefore complete resection of the tumor is recommended.