PURPOSE: This study was undertaken in order to investigate the behavior of gastrointestinal stromal tumors (GIST) of small intestine and to determine the factors related to their prognosis. METHODS: We retrospectively analyzed the clinical records of 28 patients who were diagnosed and underwent surgery for the GIST of the small intestine at Seoul National University Hospital from 1990 to 1999. RESULTS: The study group comprised 12 men and 16 women. The mean age was 48.4 years (20~78 years) at the time of diagnosis. The median follow-up period was 45 months (4~124 months). The tumor sites were the duodenum in 11 cases (39.3%), jejunum in 14 cases (50.0%) and ileum in 3 cases (10.7%). The most frequent symptom in cases of GIST of the small bowel was GI bleeing (50.0%). Complete resection of the tumor had been performed in 24 patients, and they demonstrated a longer disease-free survival time than the 4 patients who had been undergone incomplete resection, although the difference was not statistically significant (P>0.05). There were no metastases of the lymph nodes in any of the 28 cases. Eleven patients among the 24 who have been undergone complete tumor resection showed recurrence (45.8%). The mean recurrence time after surgery was 28.2 months (4~82 months) and the most common site of recurrence was the liver (81.8%). As for the univariate and multivariate analysis, the prognostic factors for the disease-free survival of patients with GIST were incresed mitotic counts of the tumor (>or=2/10 high power field) and the presence of tumor necrosis (P<0.01), although statistically there was no significant difference according to tumor size (>or=5 cm vs <5 cm; P>0.05) CONCLUSION: In cases of GIST of the small bowel, the most common symptom was GI bleeding. There were no metastases of the lymph nodes detected. The most common site of recurrence was the liver. The increased mitotic counts of the tumor and the presence of tumor necrosis were risk factors for recurrence.