Serum level of IL-31 and IL-33 was assessed in sera of 79 inflammatory bowel disease (IBD) Iraqi patients; 54 ulcerative colitis (UC) and 25 crohn's disease (CD), as well as 10 apparently healthy controls. The patients attended the Gastrointestinal Teaching Hospital in Baghdad for diagnosis and treatment during the period March-August 2012. Serum level of IL-31 was approximated in UC and CD patients and controls (1.69 ± 0.09, 1.71 ± 0.31 and 1.56 ± 0.24 pg/ml, respectively). In contrast, IL-33 was significantly increased (P ≤ 0.001) in UC and CD patients (3.29 ± 0.44 and 6.41 ± 0.18 pg/ml, respectively) compared to controls (0.74 ± 0.28 pg/ml). These results suggest a role of IL-33 in the pathogenesis of both clinical groups of IBD, especially CD.