Both toxic and physiological substances are adsorbed during an extracorporeal hemoperfusion for the treatment of exogenous and endogenous intoxications. Using a closed circuit in vitro, 1 l saline or fresh human plasma was perfused with 4425 .mu.mol creatinine, 4854 .mu.mol and 97,086 .mu.mol barbital sodium, 597 .mu.mol bromthalein, 1942 .mu.mol and 29,126 .mu.mol raffinose, and 200 .mu.mol inulin in different combinations over 70 g of uncoated charcoal. The absorptive capacity of other substances is apparently not influenced by preadsorption of the charcoal with a low or middle MW substance. In the low and middle MW range, there is no competition between 2 substances in a solution. The simultaneous usage of 2 substances of middle and high MW, or preadsorption with a high MW substance, reduces the rate of absorption and the capacity of charcoal for middle MW substances but not for low MW substances.