Different approaches to breast reconstruction have been described and nowadays nearly optimized. One major aim in further developments is to reduce donor site morbidity as low as possible. Theoretically, the lowest donor site morbidity could be achieved by using tissue that would be normally discarded during an operation necessary for a different reason. The authors present a new method of breast reconstruction in a mastectomy patient who needed a reduction mammaplasty on the remaining side in addition to the reconstruction. A single-stage split-breast flap from the reduced contralateral side pedicled on its internal mammary perforators was used, thus lowering donor site morbidity by using otherwise discarded tissue. The technical details, patient selection, advantages, possible pitfalls, management of complications, and the risk factors for contralateral malignancy are discussed.