Helicobacter pylori infection has a significant role in peptic ulcer(stomach and duodenum) , gastric cancer (adenocarcinoma, Maltoma) and chronic gastritis . Urea Breathing Test (UBT) is easy, safe, noninvasive method , because of high accuracy , it's used for early detection and also is detection method for after treatment of H.pylori infection . With due attention to cases of false negative urea breath test following the use of PPI, we intended to study effect of citric acid to reduce false-negative cases , with this insight , the PPI decreases gastric acidity and caused to inhibitory effects on H. Pylori infection but citric acid increases gastric acidity . Dyspepsia patients referred to the gastroenterology clinic of Razi Hospital, which H. Pylori with one of the methods (UBT, RUT, Stool antigen, Histology, serology) is known, enter to this study. Firstly patient profile form , filled consent and inclusion criteria included : age ≥ 18 years , detection of Helicobacter pylori infection , start treatment with PPI and exclusion criteria included : the history of previous gastric surgery , antibiotics consumption during 4 weeks before the first UBT test or during the study period , participation in a clinical study during 30 days before the screening visit , other considerable clinical disorders that researcher postulates patient is not eligible , taking H2 blocker or PPI, 2 weeks before the study, pregnancy , history of recent peptic ulcer and esophagitis , prior therapy , history of chronic liver and renal disease are examined . Urea breath test was performed for all patients if be positive , patients are included in this study then 14-day treatment period for all runs . In 13-12 days, patients are divided into two groups : urea breath test is performed in group 1 with concurrent administration of 4g of citric acid and in group 2 done without administration of citric acid . Again on days 14-15th , urea breath test is done without citric acid in group 1 and with 4g citric acid in group 2 . The results of urea breath test are studied either parallel or before and after (cross) in both study groups .