Interventional cardiology and coronary stent insertion have an increasing role in the optimal management of left main coronary artery (LMCA) stenosis. Assessing the extent of obstructive disease of the LMCA by angiography alone can be challenging. However, in contrast to the two-dimensional, shadow graphic nature of coronary angiography, intravascular ultrasound (IVUS) is an accurate tomographic technique for assessing both the coronary lumen and the vessel wall characteristics. Consequently, it is a particularly useful technique in imaging the LMCA before, during and after intervention. The European Bifurcation Club (EBC) recommends the use of IVUS during most LMCA interventions. The purpose of this consensus document is to review the available IVUS data on LMCA disease evaluation and treatment. It is a practical guide to show "how and when" to use the imaging modality. It is hoped that a standardisation of the practical approach to imaging may allow consolidation of learning and, ultimately, improve patient outcomes.