Well differentiated squamous cell carcinoma of the nasal septum developed in a 55-year old man with Wegener's granulomatosis. It is suggested that the malignancy was induced by immunosuppressive state from an increased and prolonged use of cyclophosphamide and corticosteroids. Although the efficacy of the therapeutic concept using cyclophosphamide and corticosteroids is well established, there have been some few reports that cyclophosphamide could be implicated in the genesis of malignancies. The pathophysiology of Wegener's granulomatosis should be better understood, and effective and less toxic alternative protocol should be established.