To be appropriately labelled as a ‘risk factor’ any putative risk factor should increase the prediction power of standard statistical models based on ‘traditional’ (Framingham) risk factors. In end-stage renal disease (ESRD), Framingham risk factors do not fully explain the cardiovascular burden of these patients. Inflammation, hyperhomocysteinemia and anemia contribute to the high cardiovascular risk of ESRD, but knowledge is still incomplete. We suspected that asymmetric dimethylarginine (ADMA) is an important cardiovascular risk factor in dialysis patients. This substance inhibits nitric oxide synthase thus triggering a series of pathophysiological events leading to atherosclerosis. To test this hypothesis, we studied the relationship between ADMA and intima media thickness (IMT) in the carotid artery. ADMA was found to be strongly and independently related to IMT. More importantly we found that patients with relatively higher plasma ADMA had shorter survival and a higher rate of incident cardiovascular complications in comparison to those with a relatively lower plasma concentration. These data represent a sound basis for intervention studies aimed at modifying the plasma ADMA concentration in ESRD patients.