In the plasma membranes of normal and regenerating livers at 3rd, 7th and 10th day after partial hepatectomy, Hofstee plots of calcium(Ca) binding were biphasic. The number of the low affinity binding sites(nmoles/mg membrane protein) in the membranes of regenerating livers decreased from 370 for normal liver to 170 for 3rd day, 220 for 7th day and 460 for 10th day, but their association constants slightly increased. Glucocorticoids, hydrocortisone and fluocinolone, significantly enhanced Ca binding to the membranes of normal and regenerating livers. Especially, their actions to the regenerating livers were effective even on the low concentrations. These results indicate that glucocorticoids may restore the Ca binding in regenerating liver to the normal level.