Background: Cholesterol crystal embolism (CCE) is a serious complication of vascular procedures and based on the clinical features of patients with CCE, the aim of the present study was to establish screening criteria for aortic complex plaques (ACP) at high-risk of CCE. Methods and Results: For the first study, 10 patients diagnosed as having CCE were recruited. They had prior multiple atherosclerotic disease and a high proportion of complex plaques of the carotid artery and aorta. Elevated levels of high-sensitivity C-reactive protein (hs-CRP), eosinophilia, and renal insufficiency were already recognized before CCE diagnosis. The second study prospectively enrolled 102 patients. ACP is related to CCE and predictive criteria of ACP were established. Among 19 patients with ACP, 2 presented with CCE. Multivariate analysis revealed carotid complex plaque, eosinophilia and multiple atherosclerotic risk factors as independent predictors of ACP. The criteria including these factors (multiple atherosclerotic risk factors, carotid complex plaque, hs-CRP ≥0.2 mg/dl, eGFR ≤60 ml · min^-1 · 1.73 m^-2, eosinophil count ≥400 /μl) could detect patients with ACP with 95% sensitivity, 94% specificity, and 79% positive predictive value. Conclusions: Multiple atherosclerotic risk factors, elevated hs-CRP, renal insufficiency, eosinophilia before CCE diagnosis and carotid complex plaques were features of patients with CCE. Diagnostic criteria including these characteristics effectively predict ACP patients at high-risk of CCE. (Circ J 2010; 74: 51 - 58)