In patients with end-stage renal failure physical exercise has beneficial effects on functional capacity, anemia, cardiovascular risks factors and on psychosocial problems. However, only few patients are able or willing to participate in an exercise training which is organised on an outpatient basis. As a consequence, an exercise program was developed which can be performed during hemodialysis. This program consists of a low intensity endurance training with a bed bicycle ergometer, gymnastics to increase muscular strength, flexibility and co-ordination and of relaxation techniques. An increasing number of studies show that this type of exercise training has comparable beneficial effects as an outpatient exercise rehabilitation program. In addition, exercise during hemodialysis increases the solute removal and thereby the efficiency of dialysis probably by an increased perfusion of skeletal muscles. Since 1995 this type of exercise training was implemented in about 200 German dialysis centers. The participation rate is much higher than in supervised outpatient rehabilitation programs as also elderly patients and patients with severe additional medical problems participate. Even in very old patients functional capacity is improved by exercise during dialysis. As a consequence, some patients do not need any longer professional help for the activity of daily living. Up to now no serious adverse effects or complications were induced by exercise during dialysis. This could be achieved as the patients are instructed and supervised by physiotherapists who have special knowledge and skills in renal exercise rehabilitation. Almost all patients can do some exercise during dialysis and therefore this is the most favourable type of exercise training for hemodialysis patients today.