In mammals, the functions of DMRT1 in sex determination are still ambiguous. To question its role in a non-rodent species, our laboratory generated a line of DMRT1 mutant rabbits. Throughout gonadal development, XY DMRT1-/- fetuses developed ovaries. Interestingly, some SOX9 protein remained detectable in the XY DMRT1-/- gonads even though its targets were not activated. This suggests that either these protein levels were insufficient and/or SOX9 could not act in the absence of DMRT1, which is suspected to be its pioneer factor. After birth, both XY and XX DMRT1-/- gonads did not undergo meiosis and folliculogenesis. Adult females were infertile, showing that DMRT1 is also crucial for female fertility.