This study was designed to investigate the effect of somatostatin on oocytes maturation and subsequent embryo development in cattle. Bovine granulosa cells separated from oocytes, cultured for 24 h and transfected with pEGFP-N1 vector with mouse SST gene (Experimental) and with out plasmid transfection (Control). RT-PCR and Real-Time PCR were used to estimate the expression of bovine receptors of androgen, estrogen beta, growth hormone, and follicular stimulating hormone. Culture media concentrations of hormones were measured by kits using radioimmunoassay. COCs aspirated from ovaries were co-cultured with granulosa cells layers (transfected or control) at 38.5 degrees C in CO(2) incubator for maturation. We found a significant (2.37X) increase in estrogen receptor beta expression in experimental group. There was a decrease in androgen receptor, growth hormone releasing hormone receptor, and follicular stimulating hormone receptor (P < 0.05). But, 96 h of post transfection, culture media concentration of estradiol-17beta was increased significantly (P < 0.05) and testosterone, growth hormone and follicular stimulating hormone showed opposite trend (P < 0.05) in experimental groups. Co-culture of somatostatin transfected granulosa cells with oocytes, reduced the maturation rate from 70% to 66% but had no effect on subsequent fertilization and embryo development.