Churg-Strauss syndrome is one of idiopathic, systemic necrotizing vasculitis characterized by a history of asthma or allergic rhinitis, eosinophilia of peripheral blood and variable symptoms of systemic vasculitis. There have been several recent case reports of Churg-Strauss syndrome in association with leukotriene modifier therapy when oral corticosteroids were withdrawn in asthmatic patients. We report a case of a 31-year-old man with steroid-dependent asthma who developed Churg-Strauss syndrome after 9 months of steroid withdrawal period, while he was receiving leukotriene modifier (Pranlukast).