Due to its potential prognostic implications and technical complexity, revascularisation of left main coronary artery (LMCA) disease requires careful consideration. Since publication of the results of the SYNTAX study, and more recently the EXCEL and NOBLE trials, there has been particular interest in percutaneous revascularisation of the LMCA. It is becoming clear that percutaneous revascularisation of LMCA disease requires appropriate lesion preparation and carefully optimised stenting in order to offer patients a treatment option as effective as coronary artery bypass grafting. For this reason intravascular imaging, and especially intravascular ultrasound, is becoming a key procedural step in LMCA percutaneous coronary intervention. In the current review paper we analyse the role of intravascular imaging with intravascular ultrasound in LMCA percutaneous coronary intervention, focusing on the main applications in this context from lesion assessment to stent sizing and optimisation.