Behçet’s disease (BD) is a multisystem inflammatory disorder, BDetiology remains unknown, but epidemiologic findings suggest anautoimmune process that is triggered by an infectious or environmentalagent in a genetically predisposed individual. Several viral agentsincluding cytomegalovirus, Epstein-Barr virus, and varicella zoster virus,may also have some role.Objectives: Try to assess the prevalence of CMV in Behçet’s disease,and its relation to disease activity (assessed by BDCAF).Methods: 75 Egyptian patients with Behçet’s disease as well as 75 (ageand sex matched) apparently healthy Egyptians control. All our patientswere subjected to Full history taking and thorough clinical examination.Disease activity of our patients was determined using the BDCAF.Laboratory investigations in the form of CBC, ESR, CRP, liver andkidney functions were done to all our patients. The level of CMV Ig Mand Ig G was measured by ELISA and also CMV Ig M and Ig G indiceswere calculated to all our patients and controls.Results: No significant correlation between presence of CMV Ig G, Ig Min our Behçet’s cases and controls and also between active and non activeBehçet’s cases using the BDCAF published by Leed’s University, UK,2006. Also there is no significant correlation between presence of CMVIg G, Ig M and various presentations of our Behçet’s cases. But there wassignificant correlation between cases and control in CMV Ig M index.Conclusion: The positivity of CMV Ig G and Ig M in our cases was notdifferent from those of the controls and there was no significantcorrelation between them, BDCAF and various presentations of Behçet’sdisease. There was significant correlation between cases and control inCMV Ig M index and this may raise the possibility that CMV as anetiological factor in Behçet’s disease, is not due to positivity or negativitybut may be related to the titre of positivity.