Background and aim: Inflammatory bowel disease (IBD); includes Crohn's disease (CD) and ulcerative colitis (UC) is a chronic condition. Endoscopy is the most effective method in the diagnosis of IBD, although it is an invasive, uncomfortable procedure. Pentraxin-3 (PTX-3) is a primary local inflammatory biomarker. This study aims to prove that PTX-3 shows sensitivity and specificity in the diagnosis of IBD as a non-invasive biomarker. Subjects and methods: Thirty-six (45 ± 15years) subjects, were divided into Group I (control): 12 healthy volunteers, group II: 12 CD patients and group III: 12 UC patients. Serum levels of PTX-3, antinuclear antibody (ANA) and C-reactive protein (CRP)as well as fecal calprotectin level were assessed at the start of the study and at the end of 8 weeks mesalazine treatment. Results: Results revealed a significant elevation of both calprotectin and PTX-3 levels in either CD or UC- patients in comparison to the control, with no significant difference between them regarding CRP and ANA levels. After mesalazine therapy, serum PTX-3 level was significantly decreased in both UC and CD patients, while no significant change has been detected in other studied parameters. Conclusion: PTX-3 can be used as a sensitive, specific, non-invasive inflammatory biomarker for diagnosis and follow-up of IBDs.