Abstract: Objective To investigate the value of serum peptide (Copeptin), brain natriuretic peptide (BNP) and cardiac troponin I (cTnI) in the diagnosis of acute ST segment elevation myocardial infarction (STEMI) in the elderly. Methods The changes in the levels of Copeptin, BNP and cTnI were detected in 120 cases of STEMI patients with chest pain within 4 hours (4 h), 12 hours, 24 hours, 48 hours, 5 days and healthy controls. The value of Copeptin, BNP and cTnI in the diagnosis of AMI was evaluated by ROC. Pearson correlation was used to analyze the correlation between serum Copeptin level and BNP, cTnI levels in STEMI patients. Results Serum Copeptin, BNP and cTnI levels in STEMI group at 4 hours, 12 hours, 24 hours, 48 hours and 5 days were significantly higher than those in control group (all P<0.05). In STEMI group, serum Copeptin, BNP and cTnI levels in 4 hours, 12 hours, 24 hours and 48 hours were significantly higher than 5 days (all P<0.05). In STEMI group, serum cTnI levels in 12 hours, 24 hours were significantly higher than 4 hours and 48 hours (all P<0.05). The ROC curve analysis showed that the best cut-off values of serum Copeptin, BNP and cTnI for diagnosis of elderly STEMI were 19.38 pmol/L, 1 560.74 ng/L, 6.75 ng/mL, and three combined diagnosis of senile STEMI were the highest sensitivity and specificity, 96.5% and 93.6%. Correlation analysis showed that serum Copeptin level in STEMI patients were positively correlated with BNP and cTnI levels (r=0.792, P<0.01; r=0.857, P<0.01). Conclusion Serum Copeptin, BNP and cTnI levels in elderly patients with STEMI increase significantly, the three joint detection of elderly STEMI diagnosis has high value.