A 63-year-old woman visited her local doctor complaining of acid regurgitation. Esophagogastroduodenoscopy revealed a protruding lesion with a modulated mucosal surface in the gastric antrum, with mucosal biopsies indicating well-differentiated adenocarcinoma. Because of a positive urea breathe test, while the patient was waiting for elective surgery she underwent Helicobacter pylori eradication therapy. Thirty days after eradication therapy, the patient underwent laparoscopic distal gastrectomy with regional lymph node dissection. Gross examination of the resected specimen revealed a well-circumscribed, slightly depressed lesion measuring 3.0 × 2.0 cm without elevated components. Direct effects of H. pylori eradication therapy on the morphological appearance of gastric adenomas and carcinomas have been reported. The findings in this patient suggest that the morphology of gastric cancer may be influenced directly by H. pylori eradication therapy.