Purpose: The aim of this study was to analyze the outcomes of patients with gastrointestinal stromal tumors(GISTs) of the stomach who were treated in our hospital. Materials and Methods: We retrospectively studied 31 patients who were treated for primary gastrointestinal stromal tumors of the stomach from 1990 to 1999 at Korea University Guro Hospital. Clinical characteristics, including age, sex and tumor size were analyzed. In addition, the relation between the 5-year survival rate and tumor size, operative procedure, and malignancy were analyzed to identify the factors that predict survival. Results: The malignant GISTs were 11 cases, borderline GISTs were 2 cases, and benign GISTs were 18 cases. The overall 5-year cumulative survival rate of the patients was $84.6\%$, and the 5-year survival rates according to malignancy were $100\%$ for benign and borderline GISTs and $78.1\%$ for malignant GISTs, p=0.1119. The 5-year survival rates according to tumor size were $100\%$ for tumor sizes smaller than 5 cm and $78.4\%$ for tumor sizes larger than 5 cm, p=0.0453. The 5-year survival rate according to lymph node dissection during operative procedure of malignant GISTs was not significant statistically. Conclusions: GISTs of the stomach are infrequently encountered tumors. Tumor size was the most important factor for predicting survival in a clinical situation, and performing a complete resection of the tumor, especially tumors larger than 5 cm, will improve the outcome of treatment.