A multicentre in vitro survey was carried out in 1998 in 22 European centres in order to assess the variation in the prevalence of Helicobacter pylori resistance. The susceptibility of 1,274 isolates to metronidazole, clarithromycin and amoxicillin was determined by the E test. The mean rate of resistance to metronidazole was 33.1% (95% CI, 7.5-58.9), to clarithromycin 9.9% (95% CI, 0-28.1) and to amoxicillin 0.8% (95% CI, 0-8.9). Resistance to metronidazole was significantly higher in females (P<0.001), while resistance to clarithromycin was significantly higher in children and teens (P<0.05). Resistance to both agents also tended to be higher in strains isolated from patients from southern European countries than in those isolated from patients from central or northern Europe. Overall, these results emphasize the need for further surveys of Helicobacter pylori sensitivity to antibiotics at a national and regional level.