Background: The prevalence of irritable bowel syndrome (IBS) in the community is 10%–20% and have symptom based diagnostic criteria. Many symptoms of celiac disease (CD) with 1% prevalence in some communities can mimic IBS. Sensitive and specific serologic tests of CD can detect asymptomatic cases. The purpose of this study was to compare the level of anti-tissue-transglutaminase (tTG) IgA in IBS patients and controls group. Materials and Methods: This case-control study was performed at a University hospital in which 107 patients with IBS who met the Rome II criteria for their diagnosis were compared with 126 healthy age and sex-matched controls. Both groups were investigated for CD by analysis of their serum tTG IgA antibody with human recombinant antigen. Titers were positive containing over 10u/ml and borderline if they were between 4 and 10 u/ml. Result: 86 percent of IBS patients were female. The mean antibody level was 0.837 u/ml in IBS group and 0.933 u/ml in control group without any significant difference. Discussion and Conclusion: Results of this study may intensify disagreement on the situation of CD in IBS patients.