Introduction: Cardiopulmonary fitness measured by peak VO 2 is effective in cardiovascular screening prior to renal transplantation and even predicts survival. Hypothesis: Will cardiac rehabilitation impact functional status on renal transplant candidates when compared to other factors that affect peak VO 2 Methods: A peak VO 2 test is performed with the initial transplant evaluation and repeated annually for patients on the waiting list. Peak V0 2 , heart rate max (HRmax), respiratory exchange ratio (RER), pulmonary or cardiac output limitation, deconditioning, obesity were evaluated. If any of the prior parameters were noted to be abnormal, they were acted upon. Results: A total of 107 patients (38 females and 69 males) received initial and repeat CPET testing. The average time interval between repeat tests was 342 days (11 months). The data was adjusted for various interventions to determine the magnitude to which they affected increases in peak VO 2 . The patients were able to complete an average of 36 exercise sessions (phase III) and demonstrated an average increase in peak VO 2 of 5.02 mL·min -1 ·kg -1 which was the largest difference among interventions observed. Patients that improved HRmax or RER between tests demonstrated similar changes in VO 2 (1.98, and 0.42 mL·min -1 ·kg -1 respectively). Among patients that lost weight, an average decrease of 13.1 lbs was noted with their respective increase of peak VO 2 by 0.68 mL·min -1 ·kg -1 . The initial test identified 83 patients with cardiac output limitation and 10 patients received cardiac interventions between their testing interval, resulting in an average VO 2 increase of 0.74 mL·min -1 ·kg -1 . Only 32 patients were identified to have pulmonary abnormalities from their initial test, 3 had pulmonary interventions and the average VO 2 increase was 1.53 mL·min -1 ·kg -1 Conclusion: Cardiac rehabilitation program has the highest impact on peak VO 2 that may translate into a better and healthier renal transplant candidate.