Aim To investigate the expression of serum interleukin-16 (IL-16) and copeptin in patients with acute myocardial infarction (AMI) and its clinical significance. Methods 108 patients with AMI were enrolled. The patients were divided into acute ST-segment elevation myocardial infarction (STEMI) group (55 cases) and acute non-ST-segment elevation myocardial infarction (NSTEMI) group (53 cases) according to the ECG results. Another 50 healthy volunteers who underwent physical examination were selected as the control group. Serum IL-16,copeptin, tumor necrosis factor alpha (TNF-α), IL-18, high sensitivity C-reactive protein (hs-CRP), N-terminal pro-brain natriuretic peptide (NT-proBNP), creatine kinase isoenzyme (CK-MB) and cardiac troponin I (cTnI) were detected in three groups.Results The levels of serum IL-16, copeptin, TNF-α, IL-18, hs-CRP, NT-proBNP, CK-MB and cTnI in the STEMI group were higher than those in the NSTEMI group and the control group, and the differences were statistically significant (P＜0.05). The levels of serum IL-16, copeptin, TNF-α, IL-18, hs-CRP, NT-proBNP, CK-MB and cTnI in the NSTEMI group were higher than those in the control group, the differences were statistically significant (P＜0.05). Logistic regression analysis showed that serum IL-16 had a close relationship with TNF-α, hs-CRP, NT-proBNP, CK-MB and cTnI in AMI patients (P＜0.05). Serum copeptin had a close relationship with hs-CRP, NT-proBNP, CK-MB and cTnI in patients with AMI (P＜0.05). Conclusions The levels of serum IL-16 and copeptin in patients with AMI are significantly increased, and they are closely related to the expression of some inflammatory factors and myocardial markers. It is easy to obtain serum samples, and the detection method is simple. Clinical information can be obtained by detecting the levels of IL-16 and copeptin in serum of patients with AMI.