Although many cardiovascular complications have been described in systemic lupus erythematosus (SLE), aortic involvement is rare. We report here a 51-year-old woman who suffered from SLE and died of a rupture of abdominal aortic aneurysm. She was diagnosed as having SLE in 1981, and administered prednisolone. She was admitted to our hospital for the treatment of nephrotic syndrome and hypocomplementaemia in December, 1996. Kidney biopsy revealed lupus nephritis(type IV of WHO classification). Methylprednisolone and cyclophosphamide pulse therapies were started, which resulted in an incomplete remission of nephrotic syndrome. After discharge, her clinical course was uneventful, and the dose of prednisolone was tapered. On April 22, 2001, she developed sudden abdominal pain and was admitted to a nearby hospital. Abdominal CT showed calcification of the aorta and an abdominal aortic aneurysm of 6.3 x 8 cm. She died of a rupture of abdominal aneurysm on the first hospital day. We think that prolonged prednisolone therapy might play a major role in accelerating atherosclerosis, which could result in aortic aneurysmal enlargement in this patient. Considerable attention should be paid to patients with SLE who are given prednisolone to detect and prevent vascular complications such as aneurysm.