Idiopathic pulmonary fibrosis is an increasingly recognized problem with a poor prognosis. The aetiology remains unclear. However, many patients date the onset of their disease to a recent viral infection, implying that viruses may have a potential role in disease progression. A number of studies have suggested an association between idiopathic pulmonary fibrosis and viruses including adenovirus, Epstein-Barr virus and hepatitis C. However, the molecular techniques used in identifying the viruses are extremely sensitive and may lead to erroneous associations being made. This review attempts to place into context the identification and potential role of viruses in patients with idiopathic pulmonary fibrosis.