The application of optical coherence tomography to the cardiovascular system has led to intense interest, both clinically and also on the research front. Based on sound optical physics, intracoronary, in vivo imaging with high resolution (approximately 15 microm) has given unique insights into not only atherosclerotic plaques but also the tissue responses underlying stent implantation. This article will introduce the application of optical coherence tomography technology to coronary arteries, with particular reference to the evaluation of stents, and will also give a glimpse into current and future developments that will see optical coherence tomography remain a key tool in the armamentarium of researchers and interventional cardiologists alike.