A virus-associated hemophagocytic syndrome (VAHS) is a non-neoplastic, generalized histiocytic proliferation with prominent hemophagocytosis associated with a systemic viral infection. Epstein-Barr virus (EBV) is one candidate for this association but serologic and molecular biologic studies have been lacking in many cases. Although VAHS is generally a benign process, EBV-associated hemophagocytic syndrome (EBV-AHS) is often fatal and has a relatively high mortality rate. Therefore, EBV-AHS must be distinguished from VAHS caused by other viruses. Recent evidence indicates that the pathophysiology in EBV-AHS appears to be mediated by the unrestricted release of cytokines produced by the EBV-infected T cells. Clinical and laboratory findings, the differential diagnosis, virology studies, pathophysiology, and treatment in EBV-AHS are reviewed.