---

Background and Objective: Antibiotical resistance to Helicobacter pylori reduced the eradication rates. This study was done to compare the sequential comparison of sequential and routine four drugs therapeutic regiments in Helicobacter pylori eradication. Materials and Methods: In this double blind clinical trial study 160 chronic dyspepsia patients randomly divided into 2 groups of sequential and routine four drugs therapeutic regiments. We performed invasive tests for H. pylori in patients who underwent gastroduodenoscopy. 160 patients who were diagnosed as H.pylori-positive by histological evaluation were selected for the trial. A 14-day sequential regimen (Omeprazole, Amoxicillin, each administered twice daily for the first 5 days, followed by Omprazole, Clarithromycin and Urazolidon, each administered twice daily for the remaining 9 days. 14-day 4 drug therapy, Omprazole, Clarithromycin, Amoxicillin and Bismoot each administered twice daily. 5 weeks after treatment urease breath test (UBT) was preformed. Results: The recovery was seen in 50.9% and 49.1% in sequential and routine four drugs theraputical treatment, respectively. The recovery of patient with severe H. pylori infection was non-significantly higher in sequential regiment (64.7%) than four drugs regiment (41.2%). In comparison to four drugs, sequential therapy was significantly more effective in patients with sever gastritis (87.5% vs. 25%, p<0.05). Conclusion: The eradication of H. pylori infection particularly in severe gastritis is preferred by sequential theraputical regiment.