Terahertz (THz) imaging and tomography are modern imaging techniques allowing 2D and 3D inspection of objects over a broadband frequency range. However, the transfer of this technique to medical applications is limited to surface or subsurface inspection due to the large concentration of water molecules which are an intrinsic characteristic of biological tissues. Then, we report the results of investigations led on freshly excised breast cancer tissues through reflection geometry. We focus on the dielectric response of abnormal and normal tissues respectively in the 300–500GHz. Finally, we show THz images of raw data reflection for a fresh tissue, exhibiting sufficient dielectric contrast between malignant and healthy tissues to image breast cancer.