This paper describes an approach to develop a procedure to reconstruct 3D volumes of breast cancer by using 2D ultrasonic (US) images in order to provide the shape and the dimensions of the cancer. We obtained 91.66% accuracy in the 3D reconstruction process. Breast and breast cancer phantoms were made in order to mimic acoustic properties (speed propagation). The US images of the phantoms were taken with commercial US equipment (Prosound 6, Aloka) by using a convex transducer probe (3-6MHz and 82° scanning angle), which was moved with a mechanical positioner with a resolution of 0.1mm.