Aim To investigate the alteration and clinical significance of T-helper17 cells (Th17), interleukin (IL)-17 and IL-22 in patients with acute coronary syndrome (ACS). Method 50 patients were divided into three groups: acute myocardial infarction (AMI, n20), unstable angina (UA, n15), stable angina (SA, n15) 15 healthy subjects from physical examination were used as normal control group. The peripheral blood of Th17 and Th17/Th1 cells accounted for the proportion of CD4⁺T cells were detected by flow cytometry (FCM) the concentration of plasma IL-17 and IL-22 were detected by enzyme-linked immunosorbent assay (ELISA). Results The proportion of Th17 cells in AMI group and UA group ((2.98%±1.01%) and (2.63%±0.61%)), also the proportion of Th17/Th1 cells in AMI group and UA group ((0.71%±0.35%) and (0.66%±0.31%)), were both significantly higher than SA group and normal control group (both P<0.05) IL-17 and IL-22 concentration in AMI group (IL-17: 24.41±7.95 ng/L IL-22: 34.18±7.04 ng/L) were significantly higher than SA group and normal control group (both P<0.05). IL-17 concentration in UA group (22.86±8.62 ng/L) was significantly higher than normal control group IL-22 concentration in UA group (28.98±4.35 ng/L) was significantly lower than AMI group, significantly higher than normal control group. In ACS group, there was a significant positive correlation between IL-17 concentration and IL-22 concentration (r0.422, P<0.01), also there was a significant positive correlation between the proportion of Th17 cells and IL-17 concentration(r0.722, P<0.01), IL-22 concentration(r0.400, P<0.01). Conclusions Th17 cells may be involved in the incidence of the atherosclerotic plaque instability and ACS. IL-17 and IL-22 can be used as a secondary detection of ACS diagnosis.