Currently, cardiovascular disease is the second highest cause of death globally. The occurrence and development of Acute Coronary Syndrome (ACS) have attracted attention, and inflammation has been found to play an important role in the occurrence and development of ACS. We investigated the roles of interleukin-17 (IL-17) and interferon-gamma (IFN-γ), as well as their relationship, in patients with ACS. We analysed the dynamic changes in IL-17 and IFN-γ levels in patients with ACS before and after Percutaneous Coronary Intervention (PCI). Patients were divided into the following 3 groups: (1) an Acute Myocardial Infarction (AMI) group (n=30), (2) an Unstable Angina Pectoris (UAP) group (n=30), and (3) a control group (n=30). We found that the IL-17 and IFN-γ levels were higher in the AMI and UAP groups than those in the control group. However, no significant association was observed between IL-17 and IFN-γ levels and the degree of coronary artery stenosis. A low correlation was found between IL-17 and IFN-γ levels before treatment; however, no correlation was detected after treatment. In the AMI and UAP groups, IL-17 and IFN-γ levels were significantly lower after PCI than those before PCI. IL-17 and IFN-γ may play a central role in the occurrence and development of ACS; however, their levels may not reflect disease severity. Additionally, IL-17 and IFN-γ may act synergistically in ACS. Moreover, the clinical symptoms in patients with ACS can be alleviated and inflammation in the body can be reduced through PCI.