Background Obstructive Sleep Apnea (OSA) is a worldwide increasing syndrome, which, by promoting endothelial dysfunction, contributes to extend the cardiovascular risk. We evaluated the cardiovascular risk in a group of OSA patients. Methods A total of 185 OSA subjects (19 normal weight, 57 overweight, 109 obeses), seen at the Ambulatory of Sleep Disorders, during one year, entered the study. We assessed anthropometric features, polysomnographic findings, cardiovascular risk factors, smoking habit, Pulmonary Function Test, Arterial Blood Gas Analysis, Epworth Questionnaire, and Charlson Co-morbidities Index (CCI). Subjects were divided into three groups, according to their BMI: individuals with BMI ≥30 Kg/m2 (Group 1 n=109, mean age 61 ± 1; 74.3 % males), individuals with BMI ranging from 25.0 to 29.9 Kg/m2 defined as overweight subjects (Group 2 n=57, mean age 58.8 ± 1.4; 77% males) and subjects with a BMI ranging from 18.5 to 24.9 Kg/m2 defined normal weight subjects (Group 3 n=19, mean age 54.2 ± 2.3; 64,2% males). Results In the whole population, the percentage cardiovascular risk was weakly related with BMI (r=0.33; P<0.001), but not with AHI. The cardiovascular risk was strictly related to the obesity (p<0.00002), while the Epworth Questionnaire score and the Charlson Co-morbidity Index were respectively statistically higher in the group of obese individuals (p=0.006, p=0.00002) than in the other 2 Groups. When AHI values were stratified in tertiles, the percentage cardiovascular risk did not vary with increasing AHI values (Figure 2). Conclusions Further studies are required to investigate the pivotal role of inflammation due to obesity, and underlying increased cardiovascular risk in OSA patients.