Abstract: Objective To explore the differences in magnetic resonance（MR） manifestation of different molecular subtypes of breast cancer. Methods MR images from 69 breast cancer patients were retrospectively analyzed. The morphological characteristics，early enhancement rate，time-signal intensity cure（TIC） and apparent diffusion coefficient（ADC） value of the breast cancer lesions with each molecular subtype were identified and assessed jointly. Results Among 69 cases of breast cancer，62 cases（76 lesions） showed mass-like enhancement lesions，including 8 cases of Luminal A breast cancer（11 lesions），35 cases of Luminal B breast cancer（44 lesions），9 cases of HER-2 overexpression breast cancer（11 lesions） and 10 cases of triple-negative breast cancer（10 lesions）. In mass-like enhancement lesions，the morphological difference of different molecular subtypes of breast cancer cells was statistically significant（χ²=17.006，P=0.002），and the proportion morphology of round of triple-negative breast cancer was significantly larger than the other three groups（40.00% vs 10.61%，χ²=6.390，P=0.033）. The marginal difference of different molecular subtypes of breast cancer cells was also statistically significant （χ²=25.502，P=0.001），and the proportion of circumscribed margin of triple-negative breast cancer was significantly greater than the other three groups（60.00% vs 10.61%，χ²=14.942，P=0.001）. There were no significant differences in internal enhancement characteristics，early enhancement rate，TIC type and ADC value among different molecular subtypes of breast cancer（P>0.05）. Conclusions Different molecular subtypes of breast cancer have some differences in MR manifestation，which may help distinguish between triple-negative breast cancer and non-triple-negative breast cancer. However，there is not currently possible to directly predict the molecular subtype of breast cancer based on MR manifestation. 

Key words: Breast cancer, Molecular subtypes, Magnetic resonance