The lutropin-induced depletion of ascorbate in corpora lutea of albino-rat ovary is shown to be associated with the induction of peroxidase in corpora lutea. An inverse relationship between ascorbate depletion and peroxidase activity was established in a time-course study with lutropin. Analyses made at different phases of the reproductive cycle are in accord with this relationship. It is suggested that ascorbate, which is a well-established donor in peroxidase reactions, undergoes rapid oxidation in the presence of this enzyme, producing an intermediate free radical which, if coupled with pregnenolone, might produce progesterone in the corpora lutea. The exact role of peroxidase in steroidogenesis, however, remains to be elucidated and established.