Recent data revealed that patients with myocardial infarction(MI) have a high prevalence of previously unknown diabetes mellitus(DM) and impaired glucose tolerance (IGT). The added prognostic importance of this finding has not been prospectively explored. To investigate whether a newly detected abnormal glucose tolerance (IGT or DM) assessed early after an MI, is related to long-term prognosis. Patients (n=168; age 63.5±9.3 years) with MI, no previous DM and admission blood glucose < 11.0 mmol/l were followed for major cardiovascular events defined as the composite of cardiovascular death, non-fatal MI, non-fatal stroke or severe heart failure (HF). According to an oral glucose tolerance test (OGTT) before hospital discharge, 55 patients had normal and 113 abnormal glucose tolerance (GT). During the follow-up of median 34 months there were eight cardiovascular deaths, 15 patients had a recurrent MI, six had a stroke and ten severe HF. All patients who died from cardiovascular causes had abnormal GT. The composite cardiovascular event occurred in 31(18%) patients. The probability of remaining free from cardiovascular events was significantly higher in patients with normal than abnormal GT(P=0.002). Together with previous MI, abnormal GT was the strongest predictor of future cardiovascular events (hazard ratio 4.18; CI 1.26-13.84; p =0.019). Abnormal glucose tolerance is a strong risk factor for future cardiovascular events after myocardial infarction. Since it is common and possible to detect even during the hospital phase it may be a target for novel secondary preventive efforts.