The Rating of Perceived Exertion (RPE) has been used as a supplementary tool for prescription of exercise training intensity for healthy and special populations. Despite the wide use of the RPE scale, there is an inconsistency regarding the accuracy of that scale for chronic heart failure (CHF) patients treated with beta-blockers. The study examined the correlation between RPE and heart rate (HR), percentage of maximal HR (%MHR), ventilation (VE) and oxygen consumption (VO₂) during graded treadmill testing and examined the RPE scale as a guideline for training intensity for CHF patients treated with beta-blockers. Fourteen men age 57.7 ± 10.2 yrs diagnosed with CHF and treated with beta-blockers participated in the study. During a Balke treadmill test the subjects RPE, HR, VE and VO₂ ml·kg^-1·min^-1 were monitored. Low to moderate significant correlations were found between RPE and HR, %MHR, VE and VO₂ ml·kg^-1·min^-1 (r = 0.44, 0.43, 0.55 and 0.69 respectively, all p < 0.001). Some subjects exhibited clinical symptoms (e.g. fall of systolic blood pressure, ST depression/elevation) despite relatively low RPE. The RPE may be used to indicate the level of exercise intensity; however it may not represent the HR responses in CHF patients on beta-blocker medication. Therefore, it is recommended to monitor the HR in combination with RPE when prescribing exercise intensity for CHF patients on beta blocker medication.