The anatomy of the inframammary fold has been a subject of controversy. This report describes the anatomic location and the histologic structure of the inframammary fold on the basis of caderveric dissections and microscopic examination. Ten breast cadaver dissections were performed on female cadavers (ages 35 to 72). Twenty specimens after en bloc resections of the inframammary fold and subcutaneous tissue, including the pectoralis muscle, were harvested. Specimens were examined for gross collagen stricture by using India ink to highlight the collagenous aspects of the subcutaneous soft-tissue networks. The inframammary fold skin and dermis from the contralateral breast and control samples of skin and dermis from the upper chest and the abdomen were collected for microscopic studies. These samples were stained with Sirius red and examined microscopically by polarized light. On histologic examination, regular arrays of collagen were found running parallel with the inframammary fold, and the control sections showed random patterns of collagen deposition. On gross examination, a condensation of the superficial fascial system was observed. This formed a zone of adherence between the skin and the underlying pectoralis fascia. The conclusion of this study is that the inframammary fold is an intrinsic dermal structure consisting of regular arrays of collagen held in place by a zone of adherence that is a specialized area of the superficial fascial system. The clinical significance of this study is that the intradermal structure of the inframammary fold should be preserved in any breast procedure for natural aesthetic results.