Cytomegalovirus (CMV) infection have been described as exacerbing systemic lupus erythematous (SLE). The role of CMV in starting off SLE remains object of debate. We report a severe presentation of SLE revealed by CMV infection with hemophogocytic syndrome. A 22 old women without a history of systemic disease developed a cutaneous eruption with fever and myalgia persistant for 2 weeks. Laboratory studies revealed a CMV serology supporting acute CMV infection, with positive antinuclear antidody, anti ds DNA, elevated liver functions tests, pancytopenia. Further exams revealed an hemophagocytic syndrome and a lupus nephritis. While receiving antiviral and corticosteroid therapy, the patient developed seizures related to a cerebral vasculitis. The outcome was favorable when intravenous immunoglobulins were associated. This observation showed that CMV infection in patients with SLE is often serious and difficult to diagnose and to treat, especially when SLE is not yet recognized. So we suggest all patients with recent SLE have routine testing for CMV immunity.