Abstract: AIM: To explore a new type of signaling molecule (B7-H3) in acute myocardial infarction (AMI) expression and to further investigate its relationship with the prognosis of AMI. METHODS: ELISA and immunohistochemistry were used to observe the new technology of signaling molecules B7-H3 in 116 AMI patients. Analysis was conducted on the test results of B7-H3 in AMI patients and the prognosis to determine their relationship. RESULTS: Compared with those in control group, serum levels of soluble B7-H3 protein in AMI patients were higher. In AMI patients with cardiovascular events within 1 year, plasma levels of B7-H3 were significantly higher, compared with AMI patients who had no cardiovascular events (P<0.05). CONCLUSION: Plasma B7-H3 is significantly higher in patients with AMI and the increase is, to some extent, related to the occurrence of cardiovascular events.