Cyclophosphamide (CYC) is a classical drug for the treatment of severe Wegener's granulomatosis (WG). However as it causes substantial toxicity alternative agents should be considered if optimal therapeutic CYC dose is not tolerated by an individual patient. We report the successful use of mycophenolate mofetil (MMF) in a 35-year-old patient with renal biopsy-proven pANCA WG and lung involvement. Despite a good clinical and biological response to the standard induction of remission therapy the patient developed persistent severe CYC-related leucopoenia after two months of treatment. Thus CYC was replaced by MMF; and during the three and a half years of follow-up the patient never required haemodialysis. He has remained in complete clinical remission for the last two years without MMF-related adverse effects.