Abstract Objectives Helicobacter pylori eradication remains a challenge. Non-bismuth-based quadruple regimens (NBQR) have shown high eradication rates (ER) elsewhere that need to be locally confirmed. The objective of this study was to compare the first-line ER of a hybrid therapy (20 mg of omeprazole twice daily and 1 g of amoxicillin twice daily for 10 days, adding 500 mg of clarithromycin twice daily and 500 mg of metronidazole every 8 h for the last 5 days; OA-OACM) with that of a 10 day concomitant regimen consisting of taking all four drugs twice daily every day (including 500 mg of metronidazole every 12 h; OACM). A 10 day arm with standard triple therapy (OAC; 20 mg of omeprazole/12 h, 1 g of amoxicillin/12 h and 500 mg of clarithromycin/12 h) was included. Patients and methods Three hundred consecutive patients were randomized (1: 2: 2) into one of the three following regimens: (i) OAC (60); (ii) OA-OACM (120); and (iii) OACM (120). Eradication was generally confirmed by a [13C]urea breath test at least 4 weeks after the end of treatment. Adverse events and compliance were assessed. EudraCT: 2011-006258-99. Results ITT cure rates were: OAC, 70.0% (42/60) (95% CI: 58.3–81.7); OA-OACM, 90.8% (109/120) (95% CI: 85.6–96.0); and OACM, 90.0% (107/119) (95% CI: 84.6–95.4). PP rates were: OAC, 72.4% (42/58) (95% CI: 60.8–84.1); OA-OACM, 93.9% (108/115) (95% CI: 89.5–98.3); and OACM, 90.3% (102/113) (95% CI: 84.8–95.8). Both NBQR significantly improved ER compared with OAC (P < 0.01), but no differences were seen between them. Mean compliance was elevated [98.0% (SD = 9.8)] with no differences between groups. There were more adverse events in the quadruple arms (OACM, 65.8%; OA-OACM, 68.6%; OAC, 46.6%; P < 0.05), but no significant differences between groups in terms of severity were seen. Conclusions Hybrid and concomitant regimens show good ER against H. pylori infection with an acceptable safety profile. They clearly displace OAC as first-line regimen in our area.