Of 302 patients with peptic ulcer, 11 (3.6%) proved negative for Helicobacter pylori: 9 with gastric ulcer (GU) and 2 with duodenal ulcer (DU). Among these 11 H. pylori-negative patients with ulcers, two with GU were using non-steroidal anti-inflammatory drugs (NSAIDs) and one with GU was using a corticosteroid. The Hanshin-Awaji earthquake induced life-event stress that not only triggered but exacerbated GU, particularly in the elderly, resulting in a higher GU/DU ratio than the corresponding period of the previous year (3.07 vs. 1.88) in the devastated area. Furthermore, the seroprevalence of the infection and the odds ratio from the case-control study were similar to or even higher than that reported previously in patients with GUs unrelated to the earthquake. H. pylori and the use of NSAIDs are the major independent risk factors for peptic ulcers, although, H. pylori infection plays some role in the development of peptic ulcers under stressful conditions.