The object of this study of acute anterior myocardial infarction uncomplicated by cardiogenic shock, a context in which the role of intra-aortic balloon pumping (IABP) remains controversial, was to analyse the effects of IABP on coronary flow in the culprit artery. Twenty-one patients admitted for angioplasty in the acute phase of anterior myocardial infarction were included. The IABP was performed in 6 patients (Group 1) because of clinical signs of cardiac failure. Fifteen patients (Group 2) had no signs of cardiac failure. Coronary flow velocity was recorded by a Doppler catheter after successful angioplasty. The following parameters were analysed: average peak velocity (APV), average diastolic peak velocity (ADPV), average systolic peak velocity (ASPV), diastolic to systolic velocity ratio (DSVR) and maximum peak velocity (MPV). Intra-aortic balloon pumping was associated with an increase in the diastolic indices (APV 17.9 +/- 3.5 vs 14.9 +/- 3.6 cm/s; p < 0.05; ADPV 27.6 +/- 5.2 vs 19.7 +/- 4.7 cm/s; p < 0.05), and a decrease in the systolic index ASVP (3.8 +/- 1.3 vs 7.6 +/- 2.6 cm/s; p < 0.05). The diastolic indices recorded with IABP did not change in Group 2. The velocity spectra changed with the appearance of abnormalities usually described in the presence of microcirculatory abnormalities ("no reflex" phenomenon): decrease in anterograde systolic flow, rapid deceleration of diastolic velocities with appearance of a retrograde systolic flow. The authors conclude that IABP increases diastolic velocities of coronary flow in the acute phase of revascularised anterior myocardial infarction complicated by left ventricular failure but does not seem to be accompanied by improved myocardial perfusion.