Uremic patients on hemodialysis suffer from marked reduction of physical exercise capacity. This reduction cannot solely be explained by the underlying disease and co-existing anemia. We wondered, whether reduced exercise capacity in these patients might be due to lack of physical exercise and whether anaerobic exercise training (AET) would lead to improved work capacity. 8 patients were enrolled in this study. At the beginning and at the end of the training period, which lasted 4 to 6 weeks, a symptom-limited incremental bicycle-spiroergometry was performed. AET led to a significant increase in exercise capacity without any changes in the renal status and hematocrit as well as hemoglobin values. From these data we conclude, that decreased exercise capacity in uremic patients on dialysis is due to inadequate exercise performance of these patients and that AET is able to improve exercise capacity.