Summary. Bilateral lesions were made by electrocoagulation in one of the following amygdaloid areas : basolateral, cortical or medial in adult male deermice. Animals were killed 20 days after the operation, and determinations were made of pituitary lh concentrations, hypothalamic lh-RF potencies and seminal vesicle fructose concentrations. Data indicate that lesions placed in either the basolateral or cortical amygdaloid areas, but not in the medial, result in significant increases in pituitary lh and plasma lh as interpreted by the significant increases in dry seminal vesicle weight and fructose concentrations. Hypothalamic lh-RF concentrations decline significantly in animals with medial lesions while increasing significantly in animals with basolateral or cortical amygdaloid lesions.