There is now a plethora of methods to diagnose colonization of the human stomach with Campylobacter pylori, such as microbiological culture on various media, identification of C. pylori in biopsies or biopsy smears using various stains or neurological methods, serological demonstration of specific anti-C. pylori antibodies, measuring urease activity with one of the many urease tests or using the 13C- or 14C-urea breath test. Therapy should be directed at permanent eradication of the organism. Eradication should only be diagnosed when no C. pylori organisms are demonstrable several weeks after the end of any therapy. The eradication rate with monotherapy is rather low. Combining colloidal bismuth subcitrate with an antibiotic improves the results. At present, triple therapy with colloidal bismuth subcitrate, amoxycillin or tetracycline, and metronidazole or tinidazole results in an eradication rate of over 80%. Bismuth seems to be essential in preventing antibiotic resistance formation.