Adipocytes are nowadays recognised as cells able to produce and secrete a large variety of active substances termed adipokines, which exert direct effects on vascular cells. Among these adipokines, leptin has been proposed to play a role in the pathophysiology of acute coronary syndromes, as well as in increasing cardiovascular risk. At the moment, however, the mechanisms linking leptin to cardiovascular disease are not completely understood. This study investigates the effects of leptin, in a concentration range usually observed in the plasma of patients with increased cardiovascular risk or measurable in patients with acute coronary syndromes, on tissue factor (TF) and cellular adhesion molecules (CAMs) expression in human coronary endothelial cells (HCAECs). We demonstrate that leptin induces transcription of mRNA for TF and CAMs by real-time PCR. In addition, we show that this adipokine promotes surface expression of TF and CAMs that are functionally active since we observed increased procoagulant activity and leukocyte adhesion on cell surface. Leptin effects appear modulated by eNOS-production of oxygen free radicals through the activation of the transcription factor, nuclear factor(NF)-kappaB, since L-NAME, Superoxide Dismutase and NF-kappaB inhibitors suppressed CAMs and TF expression. Data of the present study, although in vitro , indicate that leptin may exert direct effects on human coronary endothelial cells by promoting CAMs and TF expression and support the hypothesis that this adipokines, besides being involved in the pathophysiology of obesity, might play a relevant role as an active mediator linking obesity to cardiovascular disease.