Aim. To clarify the endoscopic mucosal change of the stomach caused by Lugol'sIodine solution spray on screening esophagogastroduodenoscopy (EGD). Methods. Sixty-four consecutive patients who underwent EGD for esophageal squamous cell carcinoma screening were included in this study. The records for these patients included gastric mucosa findings before and after Lugol'sIodine solution was sprayed. The endoscopic findings of the greater curvature of the gastric body were retrospectively analyzed based on the following findings: fold thickening, exudates, ulcers, and hemorrhage. Results. Mucosal changes occurred after Lugol's solution spray totally in 51 patients (80%). Fold thickening was observed in all 51 patients (80%), and a reticular pattern of white lines was found on the surface of the thickened gastric folds found in 28 of the patients (44%). Exudates were observed in 6 patients (9%). Conclusion. The gastric mucosa could be affected by Lugol's iodine; the most frequent endoscopic finding of this effect is gastric fold thickening, which should not be misdiagnosed as a severe gastric disease.