Peptic ulcer disease is the most common gastrointestinal disease. Antibiotic resistant Helicobacter pylori is a major problem worldwide. The gold standard for Helicobacter pylori eradication is composed of Proton-pump inhibitor/Ranitidine bismuth citrate + Amoxycillin + Metronidazole /Clarithromycin. In Thailand, clarithromycin resistant strains increased and led to treatment failure. Data on file at Rajavithi Hospital showed that metronidazole resistant H. pylori was about 50% and Clarithromycin resistant strains accounted for 8%. This molecular genetic study will be performed in patients presenting with dyspepsia, who had an indication for gastroscopic examination, to explore the incidence of antibiotic resistant Helicobacter pylori in Rajavithi Hospital, Thailand.