In the present study, we have estimated plasma nonrefilling rate and assessed its relationship to blood pressure stability during hemodialysis (HD) with normal or high sodium dialysate and during high flux hemodiafiltration (HDF). In standard HD, the greater plasma nonrefilling rate resulted in the larger decrease in blood pressure (α = -6.7 ± 0.2 mm Hg/%, p < 0.01, n = 75). When compared to standard HD, high flux HDF (n = 6) altered neither plasma refilling nor blood pressure stability. Finally, the restrictive usage of high sodium dialysate reduced plasma nonrefilling rate (21 ± 3 vs. 16 ± 2%, p < 0.05, n = 10) and the magnitude of decrease in blood pressure (16 ± 6 vs. 9 ± 4mm Hg, p < 0.05) without increase in interdialytic weight gain. Our data indicate relative safety of high performance HDF, and warrant judicious use of high sodium dialysate for the HD patients with hypotensive episodes.