A randomized clinical trial was recently conducted to investigate whether a new antiplatelet agent could prevent restenosis in patients who had undergone percutaneous transluminal coronary artery angioplasty (PTCA). Approximately 1,200 patients were enrolled at 13 separate clinical sites. To assess the impact of this intervention on health-related quality of life, a patient questionnaire for telephone administration was developed. This questionnaire focused attention on several specific dimensions likely to be important in this patient population: physical well-being, perceived health, emotional well-being, home management, work, recreation, and social and sexual functioning. This paper describes the instrument that was used in this trial and reports on its psychometric [corrected] properties based on completed interviews with approximately 500 patients at study entry and 1 month after PTCA.