Abstract The ability of rat oocytes to resume meiotic maturation upon isolation (“meiotic competence”) was shown to be abolished by hypophysectomy on day 15 post partum (p.p.). FSH (NIAMD-rat FSH-B-1; 10–20 μg/day), but not LH (NIAMD-oLH-21; 2–20 μg/day) was able to induce meiotic competence in rats hypophysectomixed on day 15 pp. Implantation of a capsule of oestradiol-17β, but not of progesterone or androstenedione, partially restored meiotic competence in hypophysectomized rats within 24 h of treatment. When inhibitors of steroidogenesis (aminoglutethimide, 17β-formamidoandrost-4-en-3-one, 1,4,6-androstatriene-3,17-dione or 4-hydroxy-4-androstene-3,17 dione) were coadministered with FSH they inhibited its effect on the development of meiotic competence. Furthermore, when oestradiol-17β was administered together with these inhibitors of steroidogenesis, the effect of FSH on the development of meiotic competence was not disturbed. These results strongly suggest that FSH, but not LH, is involved in the development of meiotic competence. Further, this action of FSH appears to be mediated, at least partially, by follicular oestrogen production.