Subcutaneous injections of long-acting synthetic ACTH (5 U/day) caused a large increase iin the intakes of both 0.5 M NaCl and water in rats. By the fifth day of treatment the rats were turning over an amount of sodium approximating their own total body sodium. The mineral appetite was specific for NaCl. Intakes of KCl, MgCl 2 and CaCl 2 were unchanged. ACTH was ineffective in adrenalectomized rats suggesting that the appetite was dependent on adrenal hormones.