The relationship between HP and haemodynamic changes is an area which until now has been largely uninvestigated as can be seen from the small amount of material published on this theme. The reasons for this indifference are mainly due to the low extracorporeal flow using during HP. The experiment with a new sorbent on animals must also be analyzed in cardiovascular aspects. This system is the most economical and simple for detecting the elution of vasoactive toxins. In this report the effect on the cardiovascular system of HDMTX and HP with a new trimethylammonium exchange resin versus control groups are evaluated. The results obtained clearly demonstrate the absence of haemodynamic side effects in both groups.