Background— Percutaneous coronary intervention (PCI) in a day-case setting might reduce logistic constraints on hospital resources, but data on safety are limited. We evaluated the safety and feasibility of same-day discharge after PCI. Methods and Results— Eight hundred consecutive patients scheduled for elective PCI by femoral approach were randomized to same-day discharge or overnight hospital stay. Four hours after PCI, patients were triaged as suitable for early discharge or not. Suitable patients were discharged immediately or kept overnight, according to randomization. Patients with an indication for extended hospital stay were not discharged regardless of randomization. Primary end points were death, myocardial infarction, coronary artery bypass graft surgery, repeat PCI, or puncture-related complications occurring within 24 hours after PCI. A total of 403 patients were assigned to same-day discharge, of whom 77 (19%) were identified for extended observation; 397 patients were assigned to overnight stay, of whom 85 (21%) were identified for extended observation. Among all patients, the composite primary end point occurred in 9 (2.2%) same-day discharge patients and in 17 (4.2%) overnight stay patients (risk difference, −0.020; 95% CI, −0.045 to −0.004; P for noninferiority <0.0001). Among patients deemed suitable for early discharge, the composite end point occurred in 1 of 326 (0.3%) same-day discharge patients and 2 of 312 (0.6%) overnight-stay patients (risk difference, −0.003; 95% CI, −0.014 to 0.007; P for noninferiority <0.0001). The last 3 events were related to puncture site. Conclusions— Same-day discharge after elective PCI is feasible and safe in the majority (80%) of patients selected for day-case PCI. Same-day discharge does not lead to additional complications compared with overnight stay.