In-stent neoatherosclerosis is an important contributing mechanism of late stent failure, such as very late stent thrombosis and in-stent restenosis (ISR), after both bare metal stent and drug-eluting stent implantation. However, the site-specific patterns of neointimal characteristics in ISR lesions still remain unclear. In native coronary artery disease, high-risk atherosclerotic plaques with a large necrotic core are prone to developing at bifurcation sites which are subject to abnormal conditions of endothelial shear stress. Even though bifurcation stenting has been predisposed to stent thrombosis and ISR, the frequency and distribution of unstable neointima which develops after bifurcation stenting has not been known. The aims of this study were to use optical coherence tomography (OCT) to detect advanced neoatherosclerosis in patients with ISR and characterise the patterns of neoatherosclerosis at different sites, namely restenotic lesions located at bifurcation versus non-bifurcation sites and at stent edge versus non-edge segments.