We present the completed 1-year follow-up results of the original Stent Restenosis Study (STRESS I), in which 407 patients with symptomatic ischemic heart disease and new lesions of the native coronary circulation were randomly assigned to treatment with either the Palmaz-Schatz coronary stent or conventional percutaneous transluminal coronary angioplasty (PTCA). The present study compares the safety of elective stenting to balloon angioplasty (PTCA) in terms of freedom from clinical events up to 1 year after treatment. Patients were enrolled and treated from January 1991 through February 1993, and follow-up data were collected and verified until July 1995. Ninety-seven percent of all patients had complete follow-up (deceased or alive with known clinical status) beyond 8 months, and 94% beyond 11 months. Anginal status between 9 to 15 months postprocedure was available for 78% of patients. At 1 year, 154 patients (75%) assigned to stent implantation and 141 (70%) to PTCA were free of all clinical events (death, myocardial infarction, or any revascularization procedure), and 162 stent patients (79%) and 149 PTCA patients (74%) were free from death, myocardial infarction, or target lesion revascularization. Symptom-driven target lesion revascularization occurred in 12% of the stent group versus 17% of the PTCA group. None of these differences in clinical events was statistically significant. Only 2 patients in the stent group and 7 in the PTCA group had a first event after 239 days, and freedom from angina at 1 year was reported in equal frequency in both groups (84%). There appear to be no late adverse effects of stent implantation. However, these results are limited by low statistical power, narrow patient selection, and the anticoagulation regimen used in the early experience with this device.