Background: A tubular stent may adapt with difficulty to coronary bifurcation lesions (CBLs). Methods: Time domain or frequency domain (FD) optical coherence tomography (OCT) was performed to assess strut apposition immediately after stent implantation across four segments inside the bifurcation, in a consecutive series of patients. OCT pullbacks were performed in the main vessel (MV). Results: A total of 13,142 struts in 45 CBL in 41 patients were assessed. Strut malapposition was significantly more frequent in the half bifurcation facing the side-branch (SB) ostium (42.9%) than in the proximal segment of the bifurcation 11.8%, half bifurcation opposite the SB 6.7%, or the distal segment 5.7% (all P < 0.0001). Lesions (n = 15) treated with stenting of both MV and SB had a total higher rate of malapposition than those (n = 30) treated with stenting of the MV only (17.6% vs. 9.5%; P = 0.0014). In latter group, lesions treated with FD-OCT-guided stent implantation (n = 13) presented a lower rate of malapposition than those treated with conventional angiographic-guided stent implantation (n = 17) (7.1% vs. 17.5%; P = 0.005). Conclusions: In CBL, strut malapposition is particularly high at the SB ostium. However, a strategy of stenting MV only with adjunctive FD-OCT guidance is associated with lower rates of malapposition. © 2012 Wiley Periodicals, Inc.