In mitosis, Borealin is a novel member of the chromosomal passenger complex (CPC), which is thought to play interaction roles with INCENP and survivin in the complex. Its roles in mammalian meiosis are unknown. Here, we report the expression, localization, and function of Borealin and its relation with survivin in mouse oocyte meiosis. Borealin expression was gradually increased from the germinal vesicle (GV) stage to metaphase II (MII). Immunofluorescence microscopy revealed that Borealin was weakly expressed in the GV stage and accumulated near chromosomes after germinal vesicle breakdown (GVBD). Borealin localized mainly at the spindle poles in metaphase I and anaphase I, and at the midbody in telophase. Borealin relocalized at the spindle poles during MII. Taxol and nocodazole treatment showed that the localization of Borealin was dependent on microtubule dynamics and meiotic spindle integrity, whereas survivin distribution was independent of these factors. Disruption of Borealin function by antibody injection resulted in severe spindle assembly defects, but did not affect polar body extrusion. We also found that depletion of survivin by morpholino injection had no effect on the localization of Borealin. In conclusion, our data suggest that Borealin is required for bipolar spindle formation, but may not regulate spindle checkpoint activity as a component of the CPC during mouse oocyte meiosis.