Optical coherence tomography is a recently developed high-resolution intravascular diagnostic technique. Initially, it was mainly used for characterizing atherosclerotic plaque because it served a number of functions, from identifying plaque with high lipid content to detecting macrophage accumulation, both of which are associated with plaque instability. Currently, there is growing interest in the value of optical coherence tomography in the area of coronary intervention, where the technique offers significant advantages over more widespread intravascular diagnostic techniques such as intravascular ultrasound: its higher resolution means that the vessel lumen diameter can be measured more precisely, periprocedural complications such microdissection of the coronary artery can be detected, stent apposition relative to the vessel wall can be optimized, neointimal hyperplasia can be detected after stent implantation, and neointimal thickness can be measured. It would therefore appear to be a very useful technique for interventional cardiologists. This review article considers the technical details of the technique and its applications, and compares it with other intravascular diagnostic techniques.