Widespread plaque inflammation has been demonstrated in acute coronary syndromes (ACS). We evaluated signs of plaque inflammation in carotid arteries of patients with ACS by contrast-enhanced magnetic resonance imaging (MRI). Carotid MRI was performed in 13 patients with ACS and in 9 controls having at least 1 carotid plaque with a stenosis > or =40%. MRI criteria of plaque inflammation were: increased T2 signal >50% of the plaque areas (tissue oedema) and/or enhancement after gadolinium injection (neo-vascularization). MRI signs of inflammation were found in 95% and in 33% of patients with ACS and controls, respectively (p<0.001). Carotid artery MRI may serve as a window to the entire cardiovascular system, to identify "vulnerable" patients.