Background/Aims: It is not clearly defined yet whether epidermal growth factor (EGF) is more intensely expressed at ulcer margin than at normal mucosa. This study was conducted to compare expression of EGF at ulcer margin and antral mucosa in patients with gastric ulcer and to evaluate the effect of Helicobacter pylori (H. pylori) infection on the expression of EGF. Methods: For twenty-six H. pylori positive and nine negative patients with gastric ulcer, immunohistochemical stain was performed using specific antibody against recombinant human EGF. The intensity of staining was graded as follows: 0 = no staining, 1+ = weakly positive, 2+ = intermediate between 1+ and 3+, 3+ = densely staining, equal to the level of positive control. Results: Expression of EGF was significantly more intense at ulcer margin than at antral mucosa, and tended to be more intense in active stage than in healing stage. There was no significant difference in the expression of EGF between ulcer margin and antral mucosa according to H. pylori infection status. Conclusions: Intense expression of EGF at ulcer margin and in active stage suggests that EGF plays a crucial role in ulcer healing. H. pylori status seems to have little effect on the mucosal expression of EGF. (Kor J Gastroenterol 1999;34:287 - 294)