The binding of human sex steroid-binding protein (SBP), labelled with 125I, was studied on whole cultured liver cells (Chang liver cells). SBP was shown to bind to a receptor site on normal hepatocytes. The binding was time- and temperature-dependent, highly specific and of high affinity. The liver receptor recognizing SBP was demonstrated to be different from the asialoglyco-protein receptor; in addition, laminin, which is structurally related to SBP, could not bind to the receptor. SBP was shown to recognize two binding sites with different affinities; the low affinity site was shown to possess a remarkably high capacity. This characteristic, which until now has been described only for hepatocytes, could be related to the unique role of the liver with regard to both SBP and sex steroids.