Abstract: To investigate PrRP and PrRPR mRNA expression in hypothalamuspituitaryovary axis during pregnancy，hypothalamus, pituitary and ovary were sampled on 6, 12 and 18 days of pregnancy respectively for determination of PrRP and PrRPR mRNA expression levels using semiRTPCR method. The concentration of plasma progesterone(P), estrodiol(E2) and prolactin(PRL) were measured by RIA to probe their correlations with PrRP and PrRPR mRNA. Results indicated that both PrRP and PrRPR mRNA were expressed in hypothalamus, pituitary and ovary during pregnancy. Ovary had highest PrRP mRNA level and hypothalamus had highest PrRPR mRNA level. Correlation analysis results showed that plasma P had significant negative correlation with PrRP mRNA in pituitary, and PrRP mRNA in pituitary had significant positive correlation with PrRPR mRNA in hypothalamus, which suggested that higher plasma P level during pregnancy might inhibit pituitary PrRP mRNA expression, then worked on hypothalamus to participate in pregnant regulation. The results showed that plasma PRL level had no signifant correlation with PrRP in pothalamus, pituitary and ovary,which further proved that plasma PRL level might not be regulated by tissue PrRP.