The radioligand binding assay of PHSA receptor on hepatocytes of 7 adults is reported. The presence of PHSA receptor was demonstrated in all the 7 adults, though the individual difference of the Kds and binding capacities among them was distinct with a higher standard derivation. The mean values of the Kds and binding capacities were as follows: Kd1 = 9.6769 +/- 5.2767fm-2, C1 = 86.1468 +/- 46.4129fm/micrograms; Kd2 = 103.1810 +/- 56.4770fm-2, C2 = 261.5302 +/- 175.9094fm/micrograms. The Scatchard plot was a curve which indicated the PHSA receptor on the hepatocyte was composed of two binding sites of different affinities and capacities. The possible mechanism and significance of PHSA receptor in the hepatotrophism are also discussed.