The Marfan syndrome is an autosomal dominant disorder of connective tissue, caused by mutations in the FBN1 gene on chromosome 15. More than 500 mutations have been identified and almost all are unique to an affected individual or family. Genotype--phenotype correlations in the Marfan syndrome have been complicated by the large number of unique mutations reported, as well as by clinical heterogeneity among individuals with the same mutation. A relatively unknown cardiovascular manifestation of Marfan syndrome is dilatation of the main pulmonary artery. Of 50 patients with Marfan syndrome, MR imaging showed in 74% patients an enlarged pulmonary artery root above the upper limit of normal. Aortic elasticity determined by measurement of local distensibility and flow wave velocity with MR imaging is decreased in non-operated patients with Marfan syndrome. Aortic distensibility of the thoracic descending aorta appeared to be the strongest predictor for descending aortic complications. Over the past 30 years improvement of diagnostic modalities and aggressive medical and surgical therapy, have resulted in considerable improvement of life expectancy of patients with Marfan syndrome. Further studies are needed to investigate the role of modulating genes and genotype--phenotype correlations. Long-term follow-up studies may reveal the prognostic significance of aortic elasticity and may identify patients at risk of aortic complications.