Churg-Strauss syndrome was considered rare until leukotriene modifiers were introduced into medical practice in 1996. Since then, an increasing number of reports considering a possible relationship between leukotriene receptor antagonists and the Churg-Strauss syndrome have been published. Hepatitis C virus (HCV) is a blood-borne infection and a major health problem with an increasing prevalence worldwide. Previously, numerous reports suggested a relationship between HCV and certain autoimmune disorders such as cryoglobulinaemia and polyarteritis nodosa. We present a patient with HCV seropositive Churg-Strauss syndrome and a history of systemic corticosteroid and leukotriene receptor antagonist use, and discuss the possible risk factors in the aetiology of Churg-Strauss syndrome.