In expts. involving 120 rats, the authors investigated the effect of adrenalectomy on the rate of early hepatic regeneration, and the effect of cortical extract and D.C.A. on early hepatic regeneration in adrenalectomized animals, and found that adrenalectomy decreases the deposition of fat, inhibits the deposition of protein, and prevents the increase in size and cell number normally seen in the liver remnant of rats 24 hrs. after partial hepatectomy; that adrenal cortical extract, but not D.C.A., substitutes for these functions of the adrenal; and that D.C.A. can increase the rate of hepatic regeneration in normal rats when measurements are made 5 days post-opera-tively.