To investigate the possible differences in autonomic regulation of circulation between endurance trained older subjects and older subjects who practiced moderate exercise, 10 elderly male endurance athletes, aged 65 ± 2.6 (group A), were compared with 12 male elderly subjects, aged 66 ± 3.7, who practiced moderate exercise (group B), and with a control group (group C) composed of 20 healthy younger male subjects aged 32 ± 2.3 who practiced moderate exercise. ECG holter monitoring and heart rate variability analysis data were col-lected. Episodes of heart rate below 40 beats/min were found in 4 subjects of groups A and in 1 subject of group C. The non-spectral indexes used to analyze heart rate variability are significantly higher in athletes of group A and in subjects of group C than in subjects of group B. The results of spectral analysis are in keeping with a sympathetic prevalence during the day and a vagal pre-dominance during the night, but there was lower vagal activity during the night and higher adrenergic activity during the day in sedentary subjects. Older en-durance athletes seem to have more profound bradyarrhythmias than healthy elderly controls, but the age-related decrease in heart rate variability seems to be retarded. This may have a positive prognostic value, as it may decrease the risk of life threatening ventricular arrhythmias.