Stent thrombosis is generally a fatal complication after percutaneous coronary intervention. Combined antiplatelet therapy is recommended to prevent stent thrombosis in those patients who have undergone stenting. However, there are conflicting opinions on the appropriate duration of instituting antiplatelet treatment, especially after intracoronary radiation therapy or drug-eluting stent implantation, which are two situations closely associated with an increased risk of stent thrombosis. We report here on 2 cases of late stent thrombosis that occurred despite giving combined antiplatelet therapy, and these maladies developed more than 4 years after intracoronary brachytherapy.