Induction of ovulation by means of intravenously administered cupric gluconate was tested in nonpregnant, pseudopregnant and pregnant rabbits. In nonpregnant, estrogen-pretreated rabbits, injection of more than 4 mg/kg of the compound induced ovulation in all the animals. Ovulation in these rabbits was not induced by 9 hr, but occurred between 10 and 13 hr postinjection. In pregnant and pseudopregnant animals, ovulation could not be induced by the injection of cupric gluconate, indicating a central rather than a peripheral action of this compound and suggesting inhibition of the copperactivated ovulation mechanism by humoral agents characteristic of pregnancy. (Endocrinology74: 780, 1964)