The gonadotrophins LH and FSH are known to regulate gonadal growth, and differentiation, endocrine function and gametogenesis. The LH receptor is expressed in ovarian theca, granulosa and luteal cells, and in testicular Leydig cells. The FSH receptor is expressed only in ovarian granulosa cells and in testicular Sertoli cells. The expression of the FSH and LH receptors was analysed by RT-PCR to study the role of these receptors in early mouse development. After reverse transcription, strategically designed nested primers were used for amplification from cDNA. Transcripts for the receptors were present in mouse oocytes and preimplantation embryos. The presence of mRNA for FSH and LH receptors in oocytes, zygotes and preimplantation embryos indicates a potential role for the gonadotrophins in the modulation of meiotic resumption and completion of oocyte maturation, as well as a beneficial effect on early embryonic development in mice.