Abstract: Objective: To investigate the depressant effect of two drugs, rapamycin and rosiglitazone, on the human breast cancer cell line MCF- 7, in vitro, in order to gain basic experimental data for clinical targeted therapy. Rapamycin is the specific inhibitor of the mammalian target of rapamycin (mTOR) protein and rosiglitazone is the activator of the peroxi -some prol i ferators-activated receptor γ (PPAR γ) Methods:MCF-7 cells, at logarithmic phase, were inoculated in a 24-well tissue culture plate at a concentration of 2.0 × 106 cells/well. Four experimental groups were assigned based on factorial de-sign, with the administration of drugs in three concentrations: low, medium and high. The drug concentrations were as fol-lows: Rapamycin group (4, 8, 10×10 -5 mg/L); Rosiglitazone group (25, 50, 100 μmol /L); Combination group (a combined ther-apy of 2 drugs with the low, medium and high concentrations); Control group (conventional cell culture without any treat-ment). Each drug concentration was set up in triplicate and the experiment was repeated three times. MTT colorimetric method was used to observe the inhibition of rapamycin and rosiglitazone on the growth of in vitro cultured MCF-7 cell lines. Flow cytometry was used to detect the change in apoptosis and cell cycle. Result:Both rosiglitazone and rapamycin can effectively inhibit the growth of in vitro MCF-7 cells, but the inhibitory rate of rapamycin ranked the highest (P<0.05). Rapamycin showed interference at the low and medium concentrations, while the apoptotic rate of the MCF-7 cells did not rise when the concentration was increased. The ratio of cell growth inhibition did not increase in the drug combination group (P<0.05), nor was there an increase of apoptosis ( P<0.05). There was no interaction in the drug combination of rapa-mycin and rosiglitazone at a low or medium concentration.Conclusions: The experiment of in vitro culture inhibition showed that both rapamycin and rosiglitazone can effectively inhibit the growth of human breast cancer cell line MCF- 7. Rapamycin administration combined with rosiglitazone did not increase the apoptosis of MCF- 7 cells cultured in vitro. The interference of rapamycin and rosiglitazone was completed by cycle blockage.