PURPOSE: To compare different heart rate (HR) methods commonly used to determine aerobic exercise intensity in acute leukemia patients (ALP). METHODS: 14 ALP completed a VO2peak test on a cycle ergometer with indirect calorimetry within 96 hours of admission at NC Cancer Hospital. The % of 220-age equation and HR reserve methods were compared to HR at %VO2peak at 3 different exercise intensities; low (40%), moderate (60%) and high (75%). One-Way ANOVAs were used to compare different methods at different intensities. RESULTS: No significant differences were observed between 220-age and HR at %VO2peak at moderate (100±8 and 113±24bpm, p=.122) and high intensity (125±10 and 123±25bpm, p=.994). At low intensity, all methods were significantly different. CONCLUSION: In ALP, neither % of 220-age or HR reserve should be used to prescribe aerobic exercise intensity, however, at moderate and high intensities, the 220-age equation produced similar values to HR derived from %VO2peak.