Background : Parvovirus B19 is a small DNA virus that belongs to the genus Erythrovirus . It is the cause of erythema infectiosum in children and incriminated in the pathogenesis of chronic fatigue syndrome( CFS) , which is a heterogeneous disorder of unknown pathogenesis and etiology . Objective: We aimed to determine the possible role of parvovirus B19 in the etiology of CFS. Methods : 50 patients with CFS and 45 people with no symptoms comparable with CFS as a control were investigated for specific anti B19 IgG and IgM , also B19 DNA in their sera. Results : No specific anti B19 IgM was detected in both CFS patients and control , anti B19 IgG was detected in 26 of 50 CFS patients (52%) and in 23 of 45 control (51.1%) . Also B19 DNA was found in 4 of 50 CFS cases (8%) , and in 3 of 45 control (6.7%) . There was no statistical difference between patients with CFS and control for the presence of parvovirus B19. Conclusion : B19 infection bears no apparent relationship to CFS.