Obstructive sleep apnea (OSA) has been linked to cardiovascular and cerebrovascular diseases in previous studies. However, it remains unclear whether OSA relates to cardiovascular outcomes independently of obesity and/or insulin resistance. At a tertiary referral teaching hospital, this cross-sectional analysis of 98 subjects (28 without, 39 with mild-moderate, and 31 with severe OSA) aimed to determine whether OSA relates to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) cardiovascular risk independently of obesity and insulin resistance. OSA was diagnosed by attended polysomnography. The insulin resistance index (HOMA-IR) was based on a homeostasis model assessment method. Of the patients without to those with mild-moderate to those with severe OSA, significant increases were observed in NCEP ATP III risk [median (25%, 75% quartiles) from 2.0 (1.0, 8.0) to 3.0 (1.0, 12.0) to 16.0 (5.3, 20.0)%, p <0.001 for the trend] in association with increases in HOMA-IR (p<0.001), diastolic (p=0.039) and mean blood pressure (p=0.016), serum triglycerides (p=0.047), apolipoprotein B (p=0.039), plasma fibrinogen (p=0.013), and fasting glucose levels (p=0.002). Compared with subjects without sleep apnea, patients with severe OSA had significantly higher odds for NCEP ATP III risk higher than 10% (moderately high and high cardiovascular risk) (odds ratio: 4.06, 95% confidence interval: 1.02-16.25, p=0.048) after adjustment for body mass index and HOMA-IR. These findings suggest that severe OSA is related to higher cardiovascular risk independently of obesity and insulin resistance.