We underwent protein assay for Myc expression in 76 human gastric cancer tissues using immunohistochemistry. Expression of Myc protein was analyzed according to proliferative indices measured by flow cytometry. Levels of Myc protein expression was evaluated by correlating with biologic and clinical parameters. In 36 (47.4%) of 76 primary gastric cancers, overexpression of Myc was observed. We could observe expression of Myc protein in a significant portion of early gastric cancer (42.9%). Expression of Myc protein was demonstrated to be more frequent in poorly differentiated cancer cells (p=0.043). However, expression of Myc protein had little influence over progress or extent of the disease. Expression of Myc protein was significantly correlated with increased proliferative activity (p=0.032) and patients with high levels of Myc expression had poor disease-free survival. In a certain proportion of human gastric cancer, Myc protein may function as a regulator of cancer cell growth and expression of Myc may represent an aggressive phenotype of gastric cancer.