Abstract: AIM:To study the heart rate deceleration capacity (DC) and its association with heart rate variability (HRV) in patients with acute coronary syndrome (ACS) and to assess DC as a method to detect high-risk patients with ACS. METHODS: DC and HRV parameters were measured by computer using 24-h Holter recordings of 97 patients with ACS (ACS group), 99 patients with stable angina pectoris (SAP group), and 98 healthy subjects (control group). RESULTS: Incidence of abnormal DC in the ACS group was significantly higher than that in the SAP group and control group. The median value of DC in the ACS group was significantly lower than that in the SAP group and control group. A significant positive correlation was observed between DC and HRV parameters. CONCLUSION: DC is depressed in patients with ACS. DC is a noninvasive method to assess autonomic nerve function and thus to screen high-risk patients with coronary heart disease.