Abstract:Objective To make measurement of the estradiol (E-2) and progesterone (P) level in blood serum of Mongolian gerbils, and to compare with those in NIH mice and SD rats. Method The serum E2 and P of these laboratory animals were measured by RIA and statistically analyzed. Results The serum level of E-2 in virginal and multiparous Mongolian gerbils is not significantly changed, and serum P is higher in multiparous gerbils (P<0.01). There is a significant difference between the E-2 level in virginal Mongolian gerbils and in NIH mice and SD rats (P<0.01), but similar in multiparous gerbils (P>0.05). The P level in virginal gerbils is similar to that of NIH mice, but significantly different with that in SD rats (P<0.01). The serum P level in multiparous gerbils is highest in comparison with that of NIH mice and SD rats (P<0.01). Conclusion The estradiol and progesterone levels in blood serum are species specific in Mongolian gerbils and change with the growth and development of the animals.