Churg-Strauss syndrome is an eosinophil-associated, small vessel granulomatous vasculitis, characterized by late onset asthma, upper airways disease, eosinophilia, and clinical manifestations of systemic vasculitis. Several cases of Churg-Strauss syndrome have been recognized in patients treated with cysteinyl leukotriene-receptor antagonists and weaned off systemic corticosteroids. These cases have led to a general warning on the possible development of Churg-Strauss syndrome after taking cysteinyl leukotriene-receptor antagonists. The authors report five cases of Churg-Strauss syndrome in severe steroid dependent asthmatics in whom inhaled corticosteroids allowed systemic corticosteroid withdrawal. It is concluded that physicians should monitor patients carefully when severe asthma is controlled with any substance allowing withdrawal from (or even avoidance) of systemic corticosteroids. Case-control studies should identify more precisely the risk factors of Churg-Strauss syndrome.