The aims of this paper were to assess resistance of Helicobacter pylori to antibiotics included in the so-called French triple regimens and to identify the possible causes of therapeutic failure in Reunion island. Antibiotic resistance was determined for 109 strains. All the strains were sensitive to amoxicillin and tetracycline, 93.6% were sensitive to ciprofloxacin, 92.7% to erythromycin and 60.6% to metronidazole. Fifty three patients who had previously tested positive for H. pylori received for one week regimen of amoxicillin (1 g bd), clarithromycin (0.5 g bd) and omeprazole (20 mg bd). Eradication rate after therapy was of 73.6%. Therapeutic failure was analysed for 9 patients using random amplified polymorphic DNA and the presence or not of antibiotic resistance. One cause of failure is clarithromycin resistance. These data show that triple therapy can be used in Reunion Island. In case of failure, sensitivity must be detected because the rate of resistance to metronidazole is over 30%.