The majority of post-myocardial infarction studies with beta-blocking drugs involved earlier generations. Newer drugs of this family with additional vasodilating and free-radical suppression properties, such as carvediol, are now available which may improve the prognosis still further. This double-blind, randomized, placebo-controlled, parallel group study was designed to assess the extent of myocardial ischaemia in clinically stable patients 6 weeks after acute myocardial infarction and thrombolysis, and to determine the influence of carvedilol on ischaemic events during the subsequent 6 months. One hundred and one patients who remained event free at 6 weeks post myocardial infarction underwent rest and exercise thallium-201 (TI-201) imaging. Reversible ischaemia was detected in 70 of the patients and there were 13 events in this group compared to one event in the 31 patients without ischaemia (P = 0.07). Four of the 56 patients on carvedilol and 10 of the 45 on placebo had adverse cardiac events (P = 0.04). In patients with reversible ischaemia carvedilol was more effective in reducing these events than was placebo (P = 0.03). These studies demonstrate that reversible myocardial ischaemia detected by TI-201 imaging is present in a large proportion of clinically stable patients following thrombolysis. In these patients, there is an increased cardiac event rate which is significantly reduced by carvedilol.