Although previous studies have shown the benefits of exercise training in hemodialysis patients, little is known about the effects of long-term of exercise program on these patients. We investigated the effects and the safety of long-term aerobic training and the effects of detraining on functional capacity and quality of life in hemodialysis patients. Ten patients were allocated to two groups: training and detraining. The training group completed at least 30 months of aerobic training, and the detraining group completed at least 20 months and then discontinued the training for at least 10 months. The outcomes were analyzed at baseline, after 3 months of aerobic training and at the 30-month follow-up. The training and detraining groups performed 37 (5.5) and 24 (3.0) months of aerobic training, respectively. The detraining group discontinued the training for 11.0 (2.0) months. After 3 months of aerobic training, six-minute walking test distance increased significantly in both groups (training group = 569 (287.8) vs 635.5 (277.0) m, p = 0.04; detraining group = 454.5 (72.3) vs 515.0 (91.8) m, p = 0.04). There was no significant difference in the six-minute walking test distance in the training group (576.5 (182.5), p > 0.05) and a significant decrease (436.2 (89.6) m, p = 0.04) in the detraining group at the follow-up compared to the third month of aerobic training. No significant difference was observed in quality of life during the study. No complications were found during the protocol of the exercise. These results suggest that long-term aerobic training is safe and can maintain functional capacity in hemodialysis patients. In contrast, detraining can result in loss of functional capacity in these patients.