Abstract: This article discussed the main mechanism of multidrug resistance of breast cancer tissues, and the correla-tion between technetium-99m sestamibi (⁹⁹Tc^m-MIBI) breast imaging results, with the expression of drug resistance pro-teins P-glycoprotein and glutathione-S-transfease-π in human breast cancer.Though not all the results reported before matched each other, as a kind of a noninvasive simple functional test imaging technology in vitro, SPECT can be used to diagnose P-glycoprotein expression in breast cancer, and can be used to predict chemotherapy response.