In 19 patients with advanced gastric cancer the expression of epidermal growth factor receptor and epidermal growth factor (EGF) were studied using immunohistochemical techniques. There were 12 males and the mean age of the group was 54.8 years. Most cases belonged in Borrmann's types III or IV. Tumoral cells were positive for EGF receptor in 9 patients (47%), with a strong reaction in 6. Thirteen of 18 subjects were positive for EGF. The reaction for EGF receptor was positive in 20% of 12 patients with intestinal type tumors and in 67% of 7 patients with diffuse tumors. Reaction for EGF was positive in 80% of intestinal type tumors and 64% of diffuse tumors. Simultaneous positive reactions for both antigens was observed in 5 of 18 patients, all with diffuse type tumors. Signet ring cell tumors showed less positivity than less differentiated ones. Thus, the expression of EGF and EGF receptor was higher in our patients with advanced gastric cancer than reported elsewhere.