Several non-bismuth quadruple clarithromycin-containing regimens have raised over the last decade aiming to substitute standard triple therapy (STT) for first-line H. pylori eradication therapy. Sequential therapy, introduced in Italy, involves a 5-day induction phase with dual therapy (a PPI every 12 hours and amoxicillin 1g every 12 hours), followed immediately by triple therapy for 5 days with a PPI every 12 hours, metronidazole 500 mg every 12 hours and clarithromycin 500 mg every 12 hours. 10-day sequential therapy proved more effectiveness than STT with excellent treatment compliance and minimal side effects. However, the efficacy of sequential therapy seems to be notably impaired by clarithromycin resistance and dual clarithromycin and metronidazole resistance, which is becoming a common scenario in developed countries.