A loss of volume results from a reduction in the subcutaneous fat, muscle atrophy, and changes in skeletal framework. Such loss of tissue volume compounded with tissue laxity leads to the aged appearance of the periorbital, perioral, cheek, and mandibular areas. Many facial plastic surgeons have sought to replace this volume with various injectable agents, both synthetic and autologous, in search for the ideal soft tissue filler. This article reviews the literature on lipotransfer and specifically the scientific basis underlying the approach.