Background Through precise understanding of the vascular anatomy of the breast, the lower segment of the breast could be harvested as a pedicled or free flap for contralateral breast reconstruction. Case presentation In case 1, based on the 4th intal thoracic artery perforator, the pedicled flap from the breast was transferred to the contralateral side for immediate breast reconstruction. In case 2, with the thoracoacromial vascular pedicle, the free flap from the healthy breast was harvested for delayed breast reconstruction on the contralateral side. Results Both flaps survived well postoperatively. A certain degree of asymmetry was observed in both cases, but the patients were satisfied with the overall results. At the end of follow-up, no tumor recurred in either breast. Conclusion In patients with a large healthy breast, the lower segment could be harvested as a pedicled or free flap for contralateral breast reconstruction.