XMRV is a recently discovered virus, related to mouse endogenous leukemia viruses. It was originally discovered in tissue from human prostate tumours and has been reported to be associated with chronic fatigue syndrome (CFS). Accumulating data suggest that the virus itself is a laboratory artifact and that many, if not all of the reported associations may be due to contamination of samples and or reagents. However, the association of this (and similar) viruses with chronic disease has attracted a great deal of public attention, particularly from CFS patients. Additionally, it was hypothesized that the virus might offer a risk to blood safety, generating additional pressures. Current data and perspectives on the issue will be discussed.