More than half of the known Helicobacter pylori strains are resistant to metronidazole, according to previous Hong Kong studies. The response rates to treatment regimens that comprise metronidazole as one of the antimicrobial agents have usually been disappointing in cases involving metronidazole-resistant strains. The objective of this open cohort evaluation was to assess the efficacy of an alternative regimen that combines omeprazole with amoxycillin and clarithromycin in Helicobacter pylori--positive ulcer and non-ulcer patients in Hong Kong. Furthermore, we aimed to investigate if 7 days were as good as 10 days of therapy. We studied 186 Helicobacter pylori--positive subjects; 149 subjects received 7 days of combination therapy and 37 subjects received 10 days. Our results showed that the overall Helicobacter pylori eradication efficiency was identical (94.6%) for both treatments. The incidences of adverse effects were also very similar (16.8% versus 16.2%) and both treatments were well tolerated. Thus, we propose that omeprazole in combination with amoxycillin and clarithromycin should be considered as one of the first-line therapies for patients with Helicobacter pylor infection in Hong Kong.