Behçet disease is a chronic multi-systemic disorder showing relapsing mucocutaneous, ocular, vascular and central nervous system manifestation with vasculitis as a main pathological finding. The exact etiopathology of Behçet disease is unknown with both autoimmune and auto-inflammatory mechanisms are suggested. TNFSF15 gene codes for TNF-like ligand 1A (TL1A). TL1A affects the major proinflammatory pathways. Abnormalities affecting TL1A and/or TNFSF15 were detected in many disorders i.e. ulcerative colitis, rheumatoid arthritis, and uveitis. In this research, we studied the TNFSF15 (rs3810936) polymorphism distribution and its expression in Egyptian Behçet disease patients attending to Zagazig University Hospitals. The total population of the study is 90 Egyptian individuals (30 Behçet disease patients and 60 age and sex matched healthy volunteers). TNFSF15 gene polymorphism was detected by PCR restriction fragment length polymorphism analysis. The relative expression of TNFSF15 gene was studied by quantitative real-time PCR. We concluded that the commonest genotype among Egyptian BD patients was C/T. The expression of TNFSF15 gene was not different between Behçet disease patients and controls. However, the presence of allele T influences the expression of TNFSF15. As a predictor of disease activity, TNFSF15 (rs3810936) polymorphism was not useful.