The main objective of this study is to compare the effectiveness of two sequential therapy regimens versus standard triple-drug therapy for eradication of Helicobacter Pylori in patients suffering from Dyspepsia. This study is a randomized, not blinded, single-center, not placebo controlled trial. 300 patients with Dyspepsia who have the positive Helicobacter Pylori infection based on pathological result, after performing upper endoscopy, will be enrolled in the study. Patients that need more treatments based on endoscopy results, patients with severe underlying diseases, pregnant and lactating women and patients who have allergies to drugs we want to use are excluded. These 300 patients will be randomly divided into 3 equal groups using random numbers table. Each group contains 100 patients that are the same according to age and gender. Drug regimen for these groups is as below. Group 1 (intervention): Sequential therapy with Omeprazole, Amoxicillin, Clarithromycin and Metronidazole. Group 2 (intervention): Sequential therapy with Omeprazole, Amoxicillin, Levofloxacin and Metronidazole. Group 3 (control): Standard triple therapy with Omeprazole, Amoxicillin and Clarithromycin. Patients will be visited after the completion of treatment course to be asked about side effects of drugs and 6 weeks after the treatment, they will be analyzed with Urea Breath Test (UBT). Helicobacter Pylori eradication is based on the negativity of Urea Breath Test.