Background: Cystatin C is proposed as a new marker for the glomerular filtration rate because of a constant serum level. There are few data evaluated the association of cystatin C level with heart rate recovery (HRR) which is a prognostic indicator for cardiovascular disease and all-cause mortality. Method: We measured serum cystatin C in 380 patients with known coronary artery disease and performed treadmill exercise test. HRR was calculated as the difference between maximal heart rate during exercise and hear rate 2 minutes into recovery. Result: The proportion of patients with poor HRR (less than 22 beats per minute at 2 minutes post exercise) was 12.6% among those with cystatin C levels in the highest quartile compared with 1.0% among those with cystatin C levels in the lowest quartile (p=0.002). After multivariate adjustment, independent predictors of poor HRR were greater cystatin C levels (adjusted odds ratio, 13.71, 95% confidence interval, 2.07 to 93.73; p=0.007) and increased age (adjusted odds ratio, 1.08, 95% confidence interval, 1.01 to 1.15; p=0.027). Conclusion: In patients with established coronary artery disease, cystatin C concentration was associated with decreased HRR.