There are inconsistent findings about the role of Blastocystis infection in irritable bowel syndrome (IBS). Blastocystis was detected in 19.67% of patients with IBS and 17.2% of individuals without IBS (P = 0.3). There was no significant differences in subtypes of Blastocystis between two groups (P = 0.6). Further investigations are needed to understand the role of Blastocystis in the etiology of IBS