The Bypass Angioplasty Revascularization Investigation (BARI) is a randomized multicenter clinical trial that compares a strategy of initial coronary angioplasty to initial coronary bypass surgery for patients with multivessel coronary artery disease. The purpose of this report is to describe the coronary anatomic characteristics of the 915 patients assigned to the angioplasty arm of the trial and the manner in which angioplasty was performed. Patients were eligible for BARI if they demonstrated multivessel coronary artery disease, had a clinical indication for revascularization, and were suitable for both coronary angioplasty and bypass surgery. Clinical and technical features of angioplasty procedures were systemically recorded. Coronary cineangiograms obtained before and during the angioplasty were interpreted by a central radiographic laboratory. Angioplasty was performed in 904 (98.8%) of the 915 patients assigned to that initial strategy. Of 6,530 coronary arterial lesions identified, 3,427 (52.5%) were significant (> 50% diameter reduction). The majority of patients had 2-6 significant lesions, with 3 being most common. Angioplasty was attempted in 92.2% of the lesions for which it was intended. Lesions most frequently attempted ranged between 50% and 79% in severity. Multilesion angioplasty was performed in 77.5% of patients and 69.7% had multivessel angioplasty. Factors that influenced whether a lesion was attempted included lesion severity, clinical significance, and complexity. For lesions presenting as total occlusions, a history of recent infarction and postinfarction angina favored attempting angioplasty. Patients assigned to the angioplasty arm of BARI had evidence of extensive multilesion and multivessel coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)