Intima-media thickness of the carotid artery (CIMT) and its increase is associated with several cardiovascular risk factors and manifest cardiovascular diseases. CIMT is suggested to be an important biomarker of subclinical atherosclerosis. CIMT is measured in B-mode ultrasound images of the carotid tree as a typical double line of the arterial wall. CIMT is best visible in the measurement segment of the distal common carotid artery with lowest measurement variability. The measurement is most reliable over a one centimeter-segment with automatic or semi-automatic reading methods, which minimises reading errors. Further structured training of sonographer and reader is important for valid and reproducible results. CIMT is an accepted predictor for future cardiovascular events independent of age, gender and cardiovascular risk factors. Measurement seems to be best applicable in patients with intermediate risk in order to readjust cardiovascular risk. Plaques in the carotid tree and thickening of the CIMT are different atherosclerotic processes. From childhood to early adulthood CIMT is the only atherosclerotic marker of the carotid tree; plaques occur later in life. Both parameters contribute independently to risk assessment for future cardio-vascular events. Aims of this review are to outline measurement procedures, reproducibility, prognostic value and ability to discriminate healthy subject and patients with manifest disease in a practical and scientifically contemporary manner.