Abstract: Partial cDNA sequence of rabbit BMP15 was cloned by RT-PCR from rabbit ovaries, showing a similarity of 83%−90% with the BMP15 nucleotide sequences in humans, mice, ovine, sheep, cows and pigs. The expression of BMP15 in rabbit cumulus-oocyte complexs during oocytes in vitro maturation (IVM) was measured by fluorescent quantitative RT-PCR method. BMP15 was expressed at low levels in immature oocytes and increased to the highest level at 16 h of IVM, which coincides with the time of cumulus cell expansion, then declined slowly under IVM cultivation. The expression pattern of BMP15 suggested that it might be important in cumulus expansion in rabbits.