Background: The albumin serum level is one of the most important nutritional indices and is directly correlated to the uremic patient’s hemodialysis outcome. One of the factors that can interfere with protein metabolism is the possible loss of albumin through the dialysis membrane that can contribute to keeping levels chronically low, especially for high-flux convective treatments requiring high permeability membranes and the removal of high volumes of plasma water. Methods: Twenty stable patients undergoing chronic renal replacement therapy for at least 3 months were included. Each patient performed four hemofiltration treatments, 2 in post-dilution and 2 in pre-dilution (post-D, pre-D) with a polyamide membrane (Poliflux, 2.1 m<sup>2</sup>). Results: The amount of albumin found in the ultrafiltrate was 2.9 ± 1.5 g in post-D and 1.7 ± 0.8 g in pre-D (p < 0.01). Albumin loss during online HF was lower than 3 g per treatment, and significantly lower in pre-D than in post-D. Furthermore, we observed a correlation between the transmembrane pressure and the albumin loss in both techniques, but with different slopes (y = 0.351x – 10.014 in post-dilution and y = 0.0639x + 8.2403 in pre-dilution; p = 0.01): the same transmembrane pressure determines larger albumin losses in post-dilution than in pre-dilution. Conclusions: Convective treatments that utilize high exchange volume can be performed with no risk of a significant albumin loss, particularly in pre-D where the proteic component’s contact with the dialysis membrane is lower. In post-dilution the transmembrane pressure is a relevant factor in determining the protein loss.