Aim To investigate heart rate variability (HRV) and its circadian rhythms in coronary heart disease patients with chronic congestive heart failure (CHF),and to evaluate the relationship between cardiac function and the functional lesion of autonomic nerve. Methods HRV parameters were obtained from 24 h ambulatory electrocardiogram recording. 24 h HRV in time domain and frequency domain indices were compared in 53 coronary heart disease patients with congestive heart failure (CHF),33 coronary heart disease patients with compensated heart function (CVD) and 23 healthy subjects (HS). Day and night HRV in patients with CHF were also studied. Results HRV parameters,except rMSSD,pNN50 and TI, were significantly lower in CVD than in HS (p<0.05). Time domain indices of HRV were also significantly lower in CHF than in HS (p<0.01) and in CVD (p<0.05), but there was no difference between day and night HRV frequency domain indices in patients with CHF (p>0.05). These time domain indices were markedly lower in patients with class Ⅲ-Ⅳ cardiac function than in those with classⅡcardiac function (p<0.05). Conclusion Imbalance of the autonomic nervous system were associated with coronary heart disease with compensated heart function. Sympathetic hyperactivity, lower tonic vagal activity and loss of circadian rhythms in CHF correlated with disease severity. Indices of HRV can be regarded as one of markers of prognosis in coronary heart disease patients with CHF.