In the United States, it has been reported that by the year 2030 there will be 70 million persons aged 65 years or older. In order to increase safety of the participants, and decrease the risk of complications associated with exercise, it is imperative to monitor intensity of exercise. The accuracy of self-reported heart rate (HR) as a technique to assess exercise intensity has not received as much attention within the aging population. The purpose of this investigation was to compare the accuracy of two techniques to determine exercise intensity during three modes of exercise. Thirty volunteers consisting of 12-men and 18-women with a mean age of 72.5 yrs enrolled in an exercise program were recruited as subjects. The three modes of exercise included walking, cycling, and water aerobics. The interventions were randomized and included the assessment of exercise intensity by either the radial or the carotid palpation methods. Self-reported HRs in both treatments were compared with HRs determined by Polar S-610 HR monitors. The monitors recorded subject's HR at 1-minute throughout the exercise sessions and the data were down loaded to a computer for analysis. The subjects were blinded to monitors during self-reported HR assessment. Heart rate data (mean + SD) were analyzed utilizing an independent t-test and the significance was at the p< 0.05 level. The results indicated a significantly lower self-reported HR than monitored HR during carotid palpation during cycling (89.5 bts/min + 3.7, 96.7 bts/min + 3.4) and walking (92.0 bts/min + 2.7, 103.4 bts/min + 3.9) but not during water aerobics (86.2 bts/min + 4.1, 90.0 bts/min + 2.8). No significant difference between HRs were determined during radial palpitation during cycling (93.6 bts/min + 4.7, 95.5 bts/min + 3.2) or walking (93.5 bts/min + 5.4, 98.2 bts/min + 3.6) but a significant difference existed during water aerobics (85.6 bts/min + 3.1, 93.3 bts/min + 3.1). No significant difference existed between the two techniques, with both techniques underestimating the actual HR during all assessments. The HR difference reported in three of the six measurements were significant, the practical implication appears to be less meaningful. The significant difference in the self-recorded assessment of HR for both techniques compared to the monitor may be decreased by additional subject instruction, practice, and feedback. The results suggest that either technique is acceptable for a senior population and that they should be encouraged to select the technique which they prefer. Keyword(s): adult fitness, exercise/fitness, older adult/aging issues