Aim:Both an overweight status and obesity are associated with high cardiovascular morbidity and mortality. The aim of this study was to examine the effects of obesity on different underlying mechanisms, i.e. inflammation, fibrinolysis and a prothrombotic state, in a young high-risk population in the Mediterranean area. Methods: The study population included 237 subjects (median age: 44 years). We recorded the presence of cardiovascular risk factors and premature ischaemic heart disease and performed weight stratification using the body mass index (BMI) according to the established World Health Organization (WHO) criteria. We also measured the serum/plasma lipid, fibrinogen, D-dimer, von Willebrand factor, tissue plasminogen activator antigen (t-PA), plasminogen activator inhibitor-1 antigen (PAI-1) and high-sensitivity C-reactive protein (CRP-hs) levels in samples of peripheral blood. Results: The subjects with premature ischaemic heart disease and hypertension had higher BMI values (p 0.01), and the subjects with an increased weight showed an unadjusted detrimental lipid profile, with a proinflammatory, prothrombotic state and abnormal fibrinolytic parameters. According to a multivariate analysis, the HDL-cholesterol (r 2 0.176; p 0.001), t-PA antigen (r 2 0.235; p 0.001), PAI-1 antigen (r 2 0.164; p 0.001) and CRP-hs (r 2 0.096; p 0.019) levels were significantly related to the weight stratification. Conclusions: A high BMI is a common finding in young populations at high risk of cardiovascular disease. In the current study, the patients with an increased BMI demonstrated an unhealthy lipid profile, as well as a proinflammatory and prothrombotic state and abnormal fibrinolytic parameters. J Atheroscler Thromb, 2015; 22: 610-617.