Background: Although obesity is a known risk factor for coronary artery disease, its impact on the presentation, treatment, and outcome of patients with acute coronary syndromes(ACS) has not been well studied. Methods: Using data from the CRUSADE Initiative, we compared inhospital treatments and clinical outcomes of 80 845 patients with high-risk non-ST-segment elevation(NSTE) ACS(positive cardiac markers and/or ischemic ST-segment changes) to determine whether there was an association with body mass index(BMI[kg/m2]). Patient weights were categorized according to World Health Organization classifications: Underweight(BMI< 18.5), Normal range(BMI 18.5-24.9), Overweight(BMI 25-29.9), Obese Class I(BMI 30-34.9), Obese Class Ⅱ(BMI 35-39.9), and Extremely Obese(BMI≥40). Results: Most(70.5%) of the CRUSADE patients were classified as overweight or obese; these patients were younger and more likely to present with comorbid conditions, including diabetes mellitus, hypertension, and hyperlipidemia. Medications given during the first 24 hours and invasive cardiac procedures recommended by the American College of Cardiology/American Heart Association guidelines for NSTE ACS were more commonly used in these patients. The incidence of death and death and reinfarction, adjusted for covariates, were generally lower in overweight and obese patients, compared with normal-weight patients, but higher in underweight and extremely obese patients. Conclusions: Most patients with NSTE ACS are overweight or obese. These patients receive more aggressive treatment, and, except for the extremely obese, have less adverse outcomes compared with underweight and normal-weight patients. Although obesity appears to be a risk factor for developing ACS at a younger age, it also appears to be associated with more aggressive ACS management and, ultimately, improved outcomes. Background: Although obesity is a known risk factor for coronary artery disease, its impact on the presentation, treatment, and outcome of patients with acute coronary syndromes (ACS) has not been well studied. Methods: Using data from the CRUSADE Initiative, we inhospital treatments and clinical outcomes of 80 845 patients with high-risk non-ST-segment elevation (NSTE) ACS (positive cardiac markers and / or ischemic ST-segment changes) to determine whether there was an association with body mass index (BMI [ Patient weights were categorized according to World Health Organization classifications: Underweight (BMI <18.5), Normal range (BMI 18.5-24.9), Overweight (BMI 25-29.9), Obese Class I (BMI 30-34.9) , Obese Class II (BMI 35-39.9), and Extremely Obese (BMI> 40). Results: Most (70.5%) of the CRUSADE patients were classified as overweight or obese; these patients were younger and more likely to present with comorbid conditions , including diabetes mellitus, hypertension, and hyperl Medications given during the first 24 hours and invasive cardiac procedures recommended by the American College of Cardiology / American Heart Association guidelines for NSTE ACS were more commonly used in these patients. The incidence of death and death and reinfarction, adjusted for covariates, were generally lower in overweight and obese patients, compared with normal-weight patients, but higher in underweight and extremely obese patients. Conclusions: Most patients with NSTE ACS are overweight or obese. These patients receive more aggressive treatment, and, except for the extremely obese It has less adverse outcomes compared with underweight and normal-weight patients. Although obesity appears to be a risk factor for developing ACS at a younger age, it also appears to be associated with more aggressive ACS management and, ultimately, improved outcomes.