An alternative to systemic heparin anticoagulation for HD is citrate dialysate (CD). CD contains a small amount of citric acid rather than acetic acid as the acidifying agent. The use of citrasate may lead to lower heparin requirements in hemodialysis. This is a randomized, double blinded, two-period crossover trial in HD patients to compare the effect of citrasate dialysis (CD) and usual acetic-acid based dialysate (AD) on heparin dose.