Coronary instability has been associated with multifocal plaque activation in the coronary circulation and in remote vascular districts, suggesting a systemic cause of instability, possibly inflammation. Magnetic resonance imaging offers a great potential for the detection of plaque inflammation. We describe the case of a 73-year-old female admitted for unstable angina, elevated levels of C-reactive protein and three-vessel disease, in whom carotid ultrasound examination revealed an atherosclerotic plaque of the left proximal internal carotid artery with an irregular profile and a heterogeneous echographic texture, determining a 50% stenosis. Magnetic resonance imaging of the plaque before and after contrast enhancement by gadolinium-DTPA showed the following signs of inflammation: an increased vessel wall thickness, an increased triple inversion recovery-fast spin-echo signal intensity indicative of tissue edema, and a homogeneous plaque contrast enhancement indicative of an increased capillary permeability and neovasculature. As the carotid stenosis was < 70% and did not give rise to any symptom, the patient was submitted to coronary bypass surgery without concomitant carotid endarterectomy. Two days later she developed an ischemic stroke with right brachiocrural hemiplegia. In the present case report, the simultaneous presence of coronary instability and a carotid plaque with magnetic resonance features suggestive of inflammation, which was probably responsible for the stroke complicating cardiac surgery, may indicate a multifocal plaque instability.