To observe the effect of rat medicated serum containing Zuo Gui Pills on the expression of aromatase mRNA in 3T3-L1 adipocytes. Methods: Seventy seven female sexual matured SD rats were divided into normal control group (20), sham-operated group (17), model group(8), positive control group(11), high Zuo Gui Wan group(6), low Zuo Gui Pills group(9). They were fed with the corresponding medicines in the stomach for 11 weeks. Sera was separated to test E2; sera of 2% from different rats was mixed with 3T3-L1 adipocytes neutralized in nutrient solution for 48 hours and tested to measure E2 and expression of aromatase mRNA. Results: Compared with the model group, weight of rats in high Zuo Gui Pills group and low Zuo Gui Pills group increased but there was no significant difference(P> 0.05). The level of E2 in serum of rats in high Zuo Gui Pills group and low Zuo Gui Pills group had no significant difference(P> 0.05). After 3T3-L1 adipocytes was neutralized for 48 hours, E2 in sera was (9.40±3.61)pg/ml in high Zuo Gui Wan Pills and (8.94±2.91)pg/ml in low Zuo Gui Pills group, increasing slightly compared with the model group （3.99±0.76）pg/ml. The expression of aromatase mRNA of model group was P450arom／GAPDH which was higher than the high Zuo Gui Pills group. Conclusion: Zuo Gui Pills have no significant effects on weight and the level of E2 in serum of ovariectomized rats but can improve activity of aromatase in 3T3-L1 adipocytes.