Homocystinuria is a metabolic disorder associated with defects in genes encoding for methionine metabolism enzymes. Vascular and connective tissue manifestations such as deep venous thrombosis, ectopia lentis and skeletal alterations are the major clinical features. We investigated the clinical manifestations of 5 Italian homocystinuric patients, performed mutation screening analysis on cystationine beta-synthase (CBS) gene and searched for genotype/phenotype correlations. We detected mild cardiovascular and skin connective tissue stigmas in these patients, never reported in homocystinuric patients before. We found 1 novel and 7 known mutations. Our patients carried no other mutation associated with venous thrombosis. Our data stress the importance of extending the clinical investigation for connective tissue manifestations in homocystinuric patients to all the organs/systems involved in Marfan syndrome, also suggesting long term follow-ups for cardiovascular manifestations.