High performance liquid chromatography was used to determine corticosterone concentration and transcortin binding capacity (TBC) in blood plasma of rats with bilateral adrenalectomy, before and after removal of endogenous hormones within 7 days (0.4, 0.2, 1, 2, 3, 4, 5, 7 days). During the first day TBC significantly decreased. However, concentration of protein binding sites subsequently elevated exceeding 2-fold the level of control values within the 7th day of the experiment. Concentration of 14C-immunoreactive transcortin in rat liver cytosol did not differ from control levels on the 5th day after the adrenalectomy. The adrenalectomy did not affect the transcortin affinity constant for corticosterone. These data suggest that the increased rate of blood plasma TBC was not related to activation of liver specific protein biosynthesis.