The Mannheim Carotid Intima-Media Thickness (IMT) and Plaque Consensus (2004–2006–2011) provides updated guidelines for the standardized assessment of carotid IMT and plaque in clinical trials and practice. IMT is a surrogate endpoint for cardiovascular risk, reflecting early atherosclerosis, while carotid plaque indicates advanced atherosclerotic disease. IMT is defined as a double-line pattern on ultrasound, with thickness measured from the intima-lumen interface to the media-adventitia interface. Plaque is a focal structure encroaching into the arterial lumen by at least 0.5 mm or 50% of surrounding IMT, or exceeding 1.5 mm in thickness. Standardized methods are essential for consistent data collection, improving the power of clinical trials and facilitating meta-analyses. IMT and plaque measurements should be taken in specific regions of the carotid artery, with attention to anatomical variations and interindividual differences. The consensus emphasizes the importance of distinguishing between IMT thickening and plaque formation, as they have different clinical implications. Ultrasound techniques, including B-mode imaging and color flow Doppler, are recommended for accurate assessment. The document also outlines guidelines for image acquisition, equipment settings, and measurement protocols to ensure reproducibility and reliability. IMT and plaque measurements are valuable tools for assessing cardiovascular risk, but serial monitoring is not recommended. The consensus highlights the need for standardized protocols to ensure consistency in clinical trials and research studies.The Mannheim Carotid Intima-Media Thickness (IMT) and Plaque Consensus (2004–2006–2011) provides updated guidelines for the standardized assessment of carotid IMT and plaque in clinical trials and practice. IMT is a surrogate endpoint for cardiovascular risk, reflecting early atherosclerosis, while carotid plaque indicates advanced atherosclerotic disease. IMT is defined as a double-line pattern on ultrasound, with thickness measured from the intima-lumen interface to the media-adventitia interface. Plaque is a focal structure encroaching into the arterial lumen by at least 0.5 mm or 50% of surrounding IMT, or exceeding 1.5 mm in thickness. Standardized methods are essential for consistent data collection, improving the power of clinical trials and facilitating meta-analyses. IMT and plaque measurements should be taken in specific regions of the carotid artery, with attention to anatomical variations and interindividual differences. The consensus emphasizes the importance of distinguishing between IMT thickening and plaque formation, as they have different clinical implications. Ultrasound techniques, including B-mode imaging and color flow Doppler, are recommended for accurate assessment. The document also outlines guidelines for image acquisition, equipment settings, and measurement protocols to ensure reproducibility and reliability. IMT and plaque measurements are valuable tools for assessing cardiovascular risk, but serial monitoring is not recommended. The consensus highlights the need for standardized protocols to ensure consistency in clinical trials and research studies.