AbstractRed cells labelled with Cr51and albumin labelled with I131were given i. v. to unanesthetized rabbits. Additional doses of I131‐albumin kept the plasma concentration of labelled albumin at a steady value. At different times after the first injection the animals were killed and the eyes dissected. The red cell contents of the choroid, the anterior uvea and the retina were the same at all time intervals, while the apparent volume of the plasma equivalent albumin space in the tissues increased with time. The results were analyzed in terms of intravascular and extravascular albumin compartments having the same concentration of I131‐albumin as plasma. The apparent volumes of the extravascular plasma albumin compartments were: in the choroid 112μl per g tissue, in the anterior uvea 94μl per g tissue and in the retina 4.8μl per g tissue. The apparent turnover rates for the albumin solution in the extravascular albumin compartments were: in the choroid 0.0847μl per min, in the anterior uvea 0.234μl per min and in the retina 0.0075μl per min. It was calculated that the albumin concentration in the tissue fluid of the choroid and in that of the anterior uvea as a whole is more than tenfold the albumin concentration in the aqueous humour and that the albumin drainage with the aqueous humour can account for less than 10 per cent of the albumin drainage fro