There have been little data regarding major determinants for the uncovered stent struts after drug-eluting stent (DES) implantation on optical coherence tomography (OCT). We investigated the major determinants of incomplete neointimal coverage of DES struts on OCT after implantation in a large cohort of patients. A total of 261 patients with 279 lesions who were treated with various DESs were selected from the OCT registry database. The lesions were divided into two groups based on the ratio of uncovered struts to total struts in all OCT cross-sections; an uncovered group (highest quartile with % uncovered struts ≥5.4%, n = 70), and covered group (the remaining lower quartiles with % uncovered struts <5.4%, n = 209). The uncovered group was more likely to have complex lesions, smaller reference vessel and stent diameter, and longer stent, more use of sirolimus-eluting stents, and less use of zotarolimus-eluting stents compared with the covered group. Of these variables, the most significant determinant of uncovered stent struts was DES type (odds ratio [OR] = 2.75, 95% confidence interval [CI] = 1.94-3.89, P < 0.001). The use of sirolimus-eluting stents (OR = 2.44, 95% CI, 1.15-5.47, P = 0.023) and zotarolimus-eluting stents (OR = 0.02, 95% CI = 0.01-0.25, P = 0.002) were the only significant risk and protective factors for uncovered stent struts, respectively. This study demonstrated that DES type might be associated with the most important determinants of uncovered struts compared to any other clinical or angiographic factor.