Percutaneous coronary intervention (PCI) with stent implantation is known to be effective in treating patients with coronary artery disease. Although subacute stent thrombosis (SAT) is not common, it is a life-threatening complication after PCI. We report on a 62-year-old female patient who developed SAT 3 days after drug-eluting stent implantation in the left anterior descending artery. Dipyridamole stress thallium-201 myocardial perfusion imaging (MPI) performed 3 days after PCI revealed much greater ischemic change than the pre-PCI MPI did. SAT was then confirmed subsequently by another cardiac catheterization. This suggests that MPI may be useful in diagnosing SAT.