Marfan's syndrome is characterised by clinical signs of different systems: cardiovascular (aortic dilatation, risk of dissection, mitral valve prolapse), ophthalmological with risk of blindness, rheumatological, dermatological and neurological. It is a genetic disorder, usually related to a mutation of the gene coding for type 1 fibrillin. The physiopathology has been clarified over the last few years by the implication of the TGF-beta signalling pathway. The specific receptors may be abnormal in some cases; this pathway seems paradoxically activated in the aortic wall. Its blockade in the mouse limits aortic dilatation and clinical studies are underway. While waiting for these results, present management is based on beta blocker therapy, regular checks of the aortic diameter and preventive surgery, usually with preservation of the aortic valve. The life expectancy of these patients has already increased by 30 years and this could continue in the future with an improved quality of life.