Since the report of culture of Helicobacter pylori in 1983, there has been increasing agreement that H. pylori infection is etiologically associated with a number of important diseases including chronic active gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphoma, gastric polyps, gastric cancer, as well as suggestions that it may be involved in diseases outside the upper gastrointestinal tract. There have been a number of national and international consensus meetings to propose guidelines to treat H. pylori infection. The recommendations of these conferences are reviewed here and updated to include new indications and concepts regarding H. pylori eradication therapy. Eradication therapy is considered the standard of care for active or inactive peptic ulcer patients including those who use non-steroidal anti-inflammatory drugs (NSAIDs). Other strong indications include MALT lymphoma, hyperplastic polyps, hyperplastic gastropathy, post-endoscopic resection for gastric malignancy, and acute H. pylori gastritis. Other considerations include plan to use chronic NSAID therapy, plan for chronic anti-secretory therapy, and some extra-gastroduodenal diseases such as chronic ureterica. Non-investigated dyspepsia is an indication for diagnostic evaluation and eradication therapy for those with H. pylori infection, whereas non-ulcer dyspepsia (NUD) in which peptic ulcer disease has been excluded is not an indication for evaluation per se. Intervention studies are now in progress to test the hypothesis that prevention of gastric malignancy is an outcome of H. pylori eradication. Because the prevalence of H. pylori infection and the associated diseases such as peptic ulcer or gastric cancer differ among countries as well as different approvals for treatment are required by governments or insurance agencies, the acceptable indications of eradication therapy will, by necessity, vary among countries.