The amygdaloid nuclear complex was stimulated electrochemically in two different types of persistent estrous rats and in castrated male rats bearing an ovarian transplant. In persistent estrous rats induced by continuous illumination, ovulation could be obtained by the electrochemical (EC) stimulation of the medial part of the amygdala (8 out of 12 rats), but the EC stimulation of other areas in the amygdala was ineffective in inducing ovulation. In androgenized rats (treated with 1mg testosterone propionate at 5 days of age), the EC stimulation could not induce ovulation in any of these rats. In addition, ovulation and corpus luteum formation did not occur in ovarian transplants following the EC stimulation of the amygdala in castrated male rats. These results suggest that the amygdaloid influence on the hypothalamic-pituitary gonadotrophic function in lightinduced persistent estrous rats may differ in nature from those in androgenized rats and male rats.