In recent years, the incidence of Helicobacter pylori (H. pylori) infection has been decreasing and the incidence of peptic ulcer and bleeding ulcer induced by NSAIDs, especially low-dose aspirin (LDA), have been increasing. PPI and PG are useful for treatment and prevention of ulcers in patients receiving continuous administration of NSAIDs and/or LDA. H. pylori eradication is effective if performed before the start of NSAIDs administration, but a beneficial effect of H. pylori eradication performed during NSAIDs treatment cannot be expected. The incidence of ulcers is lower when administering COX-2-selective inhibitor than when administering non-selective NSAIDs, but attention must be given to cardiovascular events as side effects when administering COX-2-selective inhibitor.