BACKGROUND: The role of ASA for primary CVD prevention is controversial. We assessed the use of ASA in healthy, middle-aged subjects in the PARADIGM study. METHODS: PARADIGM enrolled 3015 men >40 or women >50 to assess trends in CV risk assessment. Subjects with diabetes, vascular disease, or those receiving lipid lowering drugs were excluded. We report on the 406 subjects (13.5%) who were receiving ASA for primary CVD prevention. RESULTS: Subjects prescribed ASA, compared to those not, were more likely to be older (61.6 vs. 55.5y, p<0.0001), male (p<0.001), white Caucasian (88.9 vs. 66.6%, p<0.0001), past/current smokers (43.8 vs. 33.3%, p=0.0004), hypertensive (60.8 vs. 25.7%, p<0.00001), and to have a CV family history (30.9 vs. 23.3%, p=0.002). SBP, DBP, creatinine, hsCRP, waist circumference (WC) and BMI were discriminators of ASA use (all p<0.0005). LDL-c fasting glucose, IFG, and HbA1c did not differ between those prescribed ASA or not. Mean modified FRS for those prescribed ASA vs. not were 22.3 vs. 13.5% respectively (p<0.00001). Of those prescribed ASA, FRS categories were 18% low, 47.8% intermediate, and 34.2% high. In ASA-treated subjects, rates of smoking, HT, family history and mean BP, BMI and hsCRP were similar between genders. Mean HDL and LDL (both p<0.0001), glucose (p=0.05), and HbA1c (p=0.0001), were higher in women than men. Mean FRS was lower in ASA-treated women (14.4 vs. 27.0%, p<0.00001). FRS categories for ASA-treated women vs men were: low (34.4 vs 8.2%), intermediate (43 vs. 34.5%), and high (22.5 vs. 57.3%, all p<0.00001). CONCLUSIONS: In PARADIGM, 13.5% of men >40 and women >50 received ASA for primary CVD prevention. Smoking, HT, family history, hsCRP and abdominal obesity were discriminators of ASA use, yet lipid and glycemic levels were not. Two thirds of ASA-treated subjects had low/intermediate FRS. The majority of ASA use in women was in those with low or intermediate risk scores.