[Cyclophosphamide-induced pneumonitis]

Cyclophosphamide is an alkylating agent with a wide spectrum of activity against malignant tumours. Because of its pronounced immunosuppressive effect it is also frequently used in organ transplantations and in the treatment of certain autoimmune diseases. The drug has toxic side effects, however, some of which are ascribed to specific metabolites. This report describes a patient who developed cyclophosphamide associated cystitis and pneumonitis while being treated for Wegener's granulomatosis. Early recognition of the condition and discontinuation of therapy is essential for a favourable outcome.