Chronic kidney disease (CKD) patients on hemodialysis may have a modified appetite due to several factors including a lack of uremic toxins elimination. The use of medium cutoff (MCO) dialysis membranes has been suggested as an alternative to improve the removal of toxins, especially those of medium and high molecular weight. This study aimed to compare the effect of hemodialysis using MCO and high-flux membranes on the appetite and leptin levels of CKD patients.