2 experiments were conducted to investigate a possible relationship of heart rate among and within individuals and to investigate the relationship between HR level and two temporal measures of HR variability. In Exp. 1 records for 18 normal male volunteers yielded a linear relationship between the autocorrelation and HR level which was confirmed by the data collected in Exp. 2, in which repeated measurements from 1 S were taken. Another temporal measure of variability was suggested (CVT) which combined this predictable relationship between Ra and MHR. The autocorrelation had no consistent significant association with any noted behavior or training in Exp. 2, but CVT did seem to relate to behavior. The data do not support the hypothesis that resting heart rate and resting heart-rate variability ( Ra or CVT) are reliable measures of “arousal” by themselves, rather that both are highly affected by conditions usually uncontrolled in experiments. The CVT did not significantly relate to EEG measures of arousal, taken during the wakeful state in Exp. 1.