After at first having dealt with the present stage of haemoperfusion in the therapy of chronic renal insufficiency, the developmental tendencies for the haemoadsorbers to be expected are mentioned which in future allow to think of a diminution of the artificial kidney. Own results concerning the behaviour of blood compatibility and the effectivity of different active charcoals show that it is to be reckoned with the further development of unstratified adsorbents or such ones with ultra-thin layer. Comparative examinations of 4 patients from the chronic haemodialytic programme, who were treated for 4 months with the CDAK 1.8 and then for 4 months with the sorbent dialyser 1.3, could not show any essential differences in the behaviour of the low-molecular substances urea, creatinine and uric acid and of the clinical condition of the patients.