Peptic ulcers are distinguished from gastric cancer by the distinctive endoscopic presentation of gastric ulcers and gastric cancer. Gastric ulcers are characterized by neater ulcer margins, smaller ulcer areas and flatter ulcer bases. On the other hand, ulcerated gastric cancer shows untidy ulcer margins, worm-like changes, uneven and dirty ulcer base, which can be diagnosed by pathological examination. Pathological examination can clearly diagnose gastric cancer or simple ulcer. If patients with high suspicion of gastric cancer under endoscopy but pathological biopsy is negative, follow-up is required.