Purpose: The development of atherosclerosis is partially controlled by systemic factors. Local factors, including local inflammation and shear stress, may also affect the progression of carotid plaques. The aim of this study was to evaluate in patients with coronary artery disease whether intra-subject left and right carotid arteries, have similar local inflammatory activation as determined non-invasively by microwave radiometry (MR). Methods: We examined 400 carotids from 200 consecutive patients with significant coronary artery disease, as documented by coronary angiography (stenosis ≥ 50%). All patients underwent carotid artery examination by basic ultrasound imaging and MR. Carotid artery disease was defined as intima-media thickness (IMT) ≥1.2 mm. During ultrasound study, plaque texture, surface and echogenicity were analyzed. Plaques were characterized as fatty, mixed and calcified according to previous classifications. Plaque surface was classified as regular and irregular. Thermal heterogeneity (ΔT) by MR was assigned as maximal temperature along the carotid artery minus minimum. Results: Mean IMT of all carotid arteries (n=400) was 2.04±1.09 mm. Mean ΔT of all carotid arteries was 0.80±0.49°C. In carotid arteries with carotid artery disease (n=313), fatty plaques (n=52) had higher ΔT compared to mixed (n=181) and calcified (n=80) (1.23±0.55°C versus 0.87±0.44°C versus 0.67±0.49°C respectively, p<0.01). Plaques with irregular surface (n=81) had higher ΔT compared to plaques with regular (n=232) (1.20±0.45°C versus 0.76±0.48°C, p<0.01). Heterogeneous plaques (n=71) had higher ΔT compared to homogenous (n=242) (1.22±0.56°C versus 0.77±0.44°C, p<0.01). Mean ΔT was similar between left and right carotid arteries (0.78±0.48°C versus 0.84±0.52°C, p=0.12). In all carotids, there was a correlation between left and right carotid plaque ΔT (p<0.001, R=0.38). In all lesions, there was a correlation between ΔT and IMT (p<0.001, R=0.25). Conclusions: Patients with coronary artery disease have similar inflammatory activation in the carotid plaques as detected by microwave radiometry. Thus, the systemic factors producing this diffuse inflammatory activation in patients with atherosclerosis need to be further investigated.