Plasma levels of vasoactive intestinal peptide increase early after acute myocardial infarction (AMI) and are significantly higher during the first 2 weeks of AMI in survivors and younger patients (<60 years) than in those who died and in older (>60 years) patients. Data suggest that vasoactive intestinal peptide is involved in neuroendocrine activation occurring in AMI and could be regarded as a marker of the course of AMI.