Cardiovascular disease is the major cause of mortality in patients undergoing chronic hemodialysis treatment. The oxidative modification of low-density lipoprotein is a crucial step in the pathogenesis of atherosclerosis. Paraoxonase 1 (PON1) is the protein responsible for most of the antioxidant activity of high-density lipoprotein, and its reduced levels are associated with more cardiovascular events in several populations. In hemodialysis patients, reduced PON1 activity has been shown to be associated with increased cardiovascular mortality. Studies have shown that after the hemodialysis session, the activity of PON1 increases. The influence of dialyzer reuse on the activity of PON1 is unknown. We aimed to evaluate the effect of the reuse of two types of dialyzers (polynephron and polyethersulfone) on the PON1 activity of hemodialysis patients. A total of 30 patients on hemodialysis were included. Pre- and post-dialysis blood samples were collected to analyze the activity of PON1 in thefirst use of the dialyzer and in the hemodialysis session of its sixth reuse. This process was carried out with polynephron (bisphenol-free) and polyethersulfone dialyzers. We found that post-dialysis PON1 activity was significantly higher than pre-dialysis activity in both thefirst use and sixth reuse (P < 0.001). The practice of reusing the dialyzer did not interfere with the improvement of PON1 activity after the hemodialysis session.