The purpose of this study was to determine the incidence of subacute stent thrombosis related to exercise testing (ETT) or exercise training in cardiac rehabilitation (exercise cardiac rehabilitation (ECR)) and to clarify the appropriate timing of ETT and ECR in patients with acute myocardial infarction (AMI) treated with coronary stenting, because the safety and appropriate timing of ETT and ECR after coronary stenting for AMI have not been established. Forty-six institutes performing emergency percutaneous coronary intervention (PCI) for AMI were surveyed for the incidence of exercise-related subacute stent thrombosis and the timing of the start of ETT and ECR in patients with AMI in 1996-1998. Among the total 13,685 patients with AMI, 4,360 (31.9%) underwent coronary stenting. Of the 132 (3.0%) subacute stent thromboses that developed within 1 month after stenting, only one event was related to maximal ETT and occurred in a patient not receiving ticlopidine. No stent thrombosis occurred in association with submaximal ETT or ECR. In 7 institutes, maximal ETT was routinely performed at 14 days after stenting for AMI without any adverse events, and in 6 institutes, ECR was routinely started within 7 days without any adverse events. This survey found that only 21.0% of all AMI patients participated in ECR. In conclusion, subacute stent thrombosis related to ETT or ECR is extremely rare (0-0.02%) in patients with AMI, especially when they are receiving ticlopidine, and therefore ETT and ECR for stented patients with AMI need not be delayed (ie, approximately 7 days after stenting for submaximal ETT and ECR, and 14 days after stenting for maximal ETT). The rate of participation of post-AMI patients in ECR is low in Japan, even in major hospitals that are actively working in the field. (Circ J 2002; 66: 930 - 936)