Background/aims: The risk of gastric cancer is increased in patients with intestinal metaplasia. Cyclooxygenase-2 activity is crucial for gastric cancer cell survival and proliferation. We aimed to assess cyclooxygenase-2 expression in patients with intestinal metaplasia or chronic active gastritis and in patients with or without a family history of gastric cancer, i.e. a first-degree relative with gastric cancer. Materials and Methods: One hundred and six patients with histologically proven intestinal metaplasia, chronic active gastritis or normal gastric mucosa were included. Immunohistochemical staining was performed using the immunoperoxidase method. Results: Cyclooxygenase-2 expression was detected in 23.1% of normal gastric mucosa, 70.6% of chronic active gastritis, and 90.5% of intestinal metaplasia. patients. Cyclooxygenase-2 expression was significantly higher in intestinal metaplasia than in chronic active gastritis (p=0.018). Cyclooxygenase-2 expression was significantly more severe in the intestinal metaplasia group when compared to the chronic active gastritis group (p=0.017). Severe cyclooxygenase-2 expression (>60% of cells) was more frequent in the intestinal metaplasia group. Cyclooxygenase-2 expression was higher in the Helicobacter pylori-positive group when compared to the Helicobacter pylori-negative group (80.3% vs 57.1%, respectively; p=0.012). Cyclooxygenase-2 expression did not significantly differ according to presence of a first-degree relative with gastric cancer. Conclusions: Patients with intestinal metaplasia demonstrated increased presence and severity of cyclooxygenase-2 expression. Our findings suggest that cyclooxygenase-2 plays an important role in the stepwise process that eventually leads to gastric cancer. There was no statistically significant difference between the patients with and without a first-degree relative with a history of gastric cancer in terms of cyclooxygenase-2 expression.