This study was designed to clarify and define the anatomic components of the inframammary crease in the female breast. Thirteen blunt dissections of the female breast were performed in cadavers and one dissection was performed in a living patient undergoing mastectomy. During the course of these dissections, a ligament was identified. This ligament originates from the fifth rib periosteum medially and the fascia between the fifth and sixth ribs laterally. The ligament inserts distally into the deep dermis of the inframammary skin fold. Histologic sections confirmed the proximal bony origin of this structure. In three cadavers, the contralateral breast was studied as it pertains to transaxillary subpectoral mammaplasty using the Agis-Dingman dissector (Padgett Instruments, Kansas City, Mo.). If too forceful a sweep were made in the inferior portion of the dissection, the ligament would be disrupted. This separation of the ligament from its origin could lead to the “double-bubble” phenomenon. Further, the horizontal position of this ligament determines the medial versus lateral fall of the ptotic breast.