The object of our study was to identify the most useful predictor of patient prognosis in acute myocardial infarction (AMI), from 7 acute-phase cardiovascular peptides which take part in neurohumoral activation [brain natriuretic peptide (BNP), atrial natriuretic peptide (ANP), renin, aldosterone, adrenomedullin, epinephrine and norepinephrine]. In 141 consecutive AMI patients, 24 hours from onset, we evaluated plasma concentration levels of the 7 types of cardiovascular peptides and the relationships between the values of these peptides and short-term clinical prognosis, including mortality. Plasma levels of all cardiovascular peptides were significantly higher in patients who suffered mortality than in surviving patients (BNP: 1,267+/-997 pg/ml vs. 293+/-327 pg/ml, p<0.0001; ANP: 164+/-186 pg/ml vs. 64+/-76 pg/ml, p<0.001; adrenomedullin: 13.61+/-3.29 Fmol/l vs. 3.45+/-1.52 Fmol/I, p<0.0001; renin: 8.79+/-7.15 ng/ml/h vs. 4.34+/-5.10 ng/ml/h, p<0.01; aldosterone: 249+/-210 pg/ml vs. 68+/-74 pg/ml, p<0.0001; epinephrine: 3,191+/-8,360 pg/ml vs. 68+/-74 pg/ml, p<0.0001; norepinephrine: 21.8+/-46.2 ng/ml vs. 0.9+/-0.8, ng/ml p<0.0001). Multivariate analysis identified only high levels of adrenomedullin as an independent related factor of cardiogenic shock (risk ratio: 5.84, 95% C.I.: 1.80-18.95, p=0.003), and as an independent predictor of short-term mortality (risk ratio: 16.16, 95% C.I.: 1.38-189.71, p=0.03). Acute-phase neurohumoral activation, involving renin, aldosterone, epinephrine, norepinephrine, BNP, ANP, and adrenomedullin may be closely related to poor patient outcomes, including mortality. Our results suggest that acute-phase plasma adrenomedullin concentrations may be the most useful predictor of patient prognosis in the setting of AMI, out of the 7 types of cardiovascular peptides involved in neurohumoral activation.