Introduction: Recent studies have shown a relationship between H. pylori and chronic idiopathic thrombocytopenic purpura (CITP). Objective: The present study was performed to evaluate this relationship in Iranian patients. Methods: The antibody (IgG) against H. pylori was studied in sixty-two patients with CITP, comprising 25 males and 37 females (mean age: 30.38±12.23 yrs ) The patients positive for H. pylori were given quadruple therapy including omeprazol, metronidazol, amoxicillin, bismuth subcitrate for two weeks and antibody assay was repeated after six months to determine the rate of H. pylori eradication. Platelet counts at onset of the study were less than 100 ×109/L After eradication therapy, increases in platelet counts above 150×109/L and those above 30×109/L of the basal values were considered as complete and partial responses ( CR and PR) respectively. The H pylori-negative patients served as control group. Results: The study included 28 patients with H. pylori infection, including 11 males and 17 females and aged from 16-63 yrs (29.7±11.58 yrs). H. pylori infections were eradicated in 25 patients (89%) comprising 16 women and 9 men. Platelet response was achieved in 11 cases (44%) including 3CR and 8PR with mean age of 26.86±7.84 yrs. Control group did not show any significant alteration of the platelet count during the follow-up period. Conclusion: The eradication of H. pylori infection led to a good platelet response in CITP patients. It is therefore suggested to search for H. pylori infection in these patients.