Background and Aims: Physiologic measurement of myocardial perfusion in the immediate postangioplasty period may complement the angiographic assessment of the outcome of the procedure and improve our ability to identify patients at increased risk for a suboptimal late result. Immediate in-lab identification of patients at risk for late coronary restenosis would allow the interventionalist to implement alternate interventional and/or pharmacologic strategies aimed at improving the long-term outcome of angioplasty. The present single-center pilot study was undertaken to examine prospectively the value of intracoronary Doppler flow measurements immediately postangioplasty for predicting long-term patency of the dilated coronary artery. Patients and Methods: Coronary average peak flow velocity (APV) at rest and during hyperemia (6-18 µg intracoronary adenosine) and coronary flow reserve in the distal coronary segment were measured in 24 consecutive patients 10-15 min after successful elective coronary angioplasty. Volume flow (Q) was calculated as APV/2· coronary cross-sectional area •heart rate. Coronary arterial vessels and narrowings were measured by quantitative angiography using a geometric based method and automated edge detection. The present study reports the findings in the 16 patients undergoing conventional balloon angioplasty for whom hard endpoint angiographic data were available 4.9 ± 1.5 months after angioplasty. Results: A linear relation was present between angiographically measured minimal luminal dimension immediately postangioplasty and the late angiographic result of the procedure (r = 0.71, p = 0.0005). A greater acute gain during angioplasty was predictive of a larger luminal dimension at late angiographic follow-up (p = 0.006). There was no relation between the immediate postangioplasty Doppler flow measurements and the late angiographic result of the procedure. Late luminal dimension was not related to immediate postangioplasty basal or hyperemia APV, nor to immediate postangioplasty basal or hyperemic volume flow or to coronary flow reserve (all NS). Conclusions: In this single-center study, intracoronary blood flow and Doppler-derived coronary flow reserve immediately postpercutaneous transluminal coronary angioplasty were not predictive of long-term vessel patency or late coronary restenosis. The immediate angiographic result of angioplasty did correlate with the late result of the procedure.