Fibromyalgia syndrome (FMS), a condition characterized by widespread pain and diffuse tenderness, is considered a multifactorial disorder. FMS is now recognized as one of the "central" pain syndromes. Environmental and genetic factors play a role in the pathogenesis of FMS. Various triggers including trauma and stress as well as infections, may precipitate the development of FMS. Certain infections including hepatitis C virus, HIV and Lyme disease have been temporally associated with the development of FMS. There is some evidence for the possible role of vaccinations in triggering the development of FMS and related syndromes, however this association remains to be established.