Aim: Irritable bowel syndrome (IBS) is a functional gastrointestinal system disease which reduces the quality of life due to abdominal pain secondary to defecation change and it has a high prevalence in society. It is known that inflammation and changes in immune system have a role in the pathogenesis of IBS. Materials and Methods: In this study, we aimed to investigate retrospectively the erythrocyte and platelet counts of patients with IBS and compare them to those of healthy controls. Files of 30 patients with IBS and 30 healthy people (both groups aged 18-50), who consulted to gastroenterology clinic in Namik Kemal University Faculty of Medicine, were scanned. The erythrocyte and platelet counts of these people as well as their demographics were recorded. Results: It was seen that RBC, HGB, HCT, MCV, MCH, MCHC, RDWCV and RDWSD levels did not differ in patients with IBS compared with the control group. Similarly, we found that PLT, MPV, PDW, PCT and PLCR did not differ in patients with IBS compared with the control group. Conclusion: We are of opinion that complete blood erythrocyte and platelet counts could not be used as prognostic marker in the diagnosis of IBS.