Background: Obesity and cardiovascular disease are closely related. Leptin, an adipocyte-produced hormone, is associated with increased cardiovascular risk. Increased plasma levels of leptin are measurable in the plasma of obese individuals. However, the possible links between obesity and cardiovascular disease are not completely understood. C-reactive protein (CRP) is a predictor of future cardiovascular events and plays a role in atherothrombotic disease. Thus, we evaluated whether leptin might play a role in cardiovascular disease, investigating its effects on CRP production by human coronary artery endothelial cells in culture. Methods and Results: Leptin induced CRP mRNA transcription as demonstrated by semiquantitative and real-time polymerase chain reaction as well as the release of CRP in the culture medium in a concentration-dependent fashion. Leptin-induced production of CRP was mediated through the RhoA activation of protein kinase Cβ since both protein kinase C and RhoA pathway inhibitors prevented these leptin effects. Lovastatin, a hydroxymethylglutaryl coenzyme A reductase inhibitor, by modulating the RhoA activation, significantly reduced leptin-induced CRP production. Conclusions: This study describes the close relationship between leptin and CRP, providing support to the view that this adipokine, besides being involved in the pathophysiology of obesity, might play a relevant role as an active partaker in obesity, inflammation and atherothrombosis.