Summary.1 Iron absorption tests were performed in rabbits. In 34 experiments 100 mg of ferrous iron was administered orally.2 20–60 minutes after iron administration the animals were laparotomized in Numal narcosis. Puncture of vena porta and vena cava, in a small group of experiments also vena hepatica and vena duodenalis, was performed.3 In 32 experiments out of 34 the serum iron level of the porta blood was higher than that of the cava blood. The difference varied between ‐8 and +214 γ%, with an average value of + 46,9 ± 8,1 γ%.4 The high serum iron level of the porta blood during iron absorption reflects the enrichment with iron during the passage through the digestive tract. To some extent the difference between porta and cava blood could be explained by the fact that it is necessary in order to heighten the serum iron level of the total blood volume. But the big differences often observed could be explained only by the assumption that iron is taken up by the liver from the porta blood. In some experiments the retention of iron in the liver could be directly demonstrated by means of comparison of the serum iron level of the porta blood and the