Conjugation and excretion of bile acids and metabolism of taurine 35S were studied in the isolated perfused liver from normal and x-irradiated rats. More bile acids are present and more were synthesized after irradiation. Taurine was removed more rapidly by the irradiated liver if no bile acids were added. No difference existed between normal and irradiated liver with respect to conversion of deoxycholate to cholate, conjugation of bile acids and the general excretion pattern of bile steroids and phospholipids.