SummaryExercise testing and myocardial T1–201 scintigraphy was performed in 21 patients within a six week period before and after succesfull percutaneous transluminal coronary angioplasty (PTCA). All patients had one vessel disease. Before PTCA ten patients had typical anginal pain during exercise testing. After PTCA none had anginal pain during exercise testing (p<0,01).The number of patients with abnormal exercise ECG decreased from nine to one (p<0,02) and with an exercise T1–201 perfusion defect from twenty to five (p<0,001). After PTCA median of maximal (MM) total work performed increased from 3450 to 5100 kpm (p<0,01), MM rate pressure product from 20320 to 28120 (p<0,01) and MM oxygen consumption from 1185 to 1797 ml/min (p<0,01). This study demonstrates the physiologic efficacy of a successful PTCA in patients with single vessel disease on regional coronary perfusion and exercise tolerance. The value of myocardial T1–201 scintigraphy in detecting patients with single vessel disease is emphasized.