BACKGROUND Patients with obesity, diabetes, and chronic kidney disease (CKD) are generally physically inactive, have a high mortality rate, and may benefit from an exercise program. METHODS We performed a 24-week randomized controlled feasibility study comparing aerobic exercise plus optimal medical management to medical management alone in patients with type 2 diabetes, obesity (body mass index [BMI] > 30 kg/m2), and stage 2-4 CKD (estimated glomerular filtration rate [eGFR] 15-90 mL/min/1.73 m2 with persistent proteinuria). Subjects randomized to exercise underwent thrice weekly aerobic training for 6 followed by 18 weeks of supervised home exercise. The primary outcome variable was change in proteinuria. RESULTS Seven subjects randomized to exercise and 4 control subjects completed the study. Exercise training resulted in an increase in exercise duration during treadmill testing, which was accompanied by slight but insignificant decreases in resting systolic blood pressure and 24-hour proteinuria. Exercise did not alter GFR, hemoglobin, glycated hemoglobin, serum lipids, or C-reactive protein (CRP). Caloric intake and body weight and composition also did not change with exercise training. CONCLUSIONS Exercise training in obese diabetic patients with CKD is feasible and may have clinical benefits. A large-scale randomized controlled trial to determine the effects of exercise on renal functions, cardiovascular fitness, inflammation, and oxidative stress in diabetic patients with CKD is planned.