Aim: To investigate the effect of exercise on dialysis adequacy during hemodialysis (HD). Methods: 20 studies were performed in 20 maintenance hemodialysis patients. Each study consisted of a pair of HD treatment; the blood and dialysate flow rates, dialyser and treating time were the same. An adapted exercise cycle was attached to the dialysis bed. The patients of exercise group pedaled the exercise cycle throughout the dialysis, and had a 5 - 10 minutes rest if they needed. while the patients of a control group had no exercise. BUN, Scr and UA were measured just before and after dialysis immediately, and 60 minutes after dialysis. Furthermore, Kt/V, SRI, AUR and nPCR were detected by on-line dialysis monitor. Results: In the exercise group, after HD, both BUN and Scr decrease rate were significantly higher (P < 0.05, t = 2.129 - 2.676) while the rebound of BUN, Scr and UA were significantly lower than those in the control group (P < 0.05 - 0.01, t = 2. 329 - 4.154). Kt/V, AUR and SRI were significant higher in the exercise group than those in the control group (P < 0.05 - 0.01, t = 2.253 - 3.997, respectively), while nPCR showed no significant difference between the two groups. Conclusion: Exercise during HD is a practicable way to improve the efficiency of dialysis as well as cheap and simple.