Free fat graft autotransplantation for soft-tissue replacement has been a neglected subject in recent years. In a review of the literature, investigations of the various uses of free fat autotransplantation in animals and humans provide an understanding of the problems associated with the use of fat as a free graft. Results of free fat autotransplantation were found to be quite unpredictable, with wide variations in the resulting bulk of the graft. Microscopic studies of this behavior led to controversy as to whether the graft ultimately was made of surviving graft adipocytes (cell survival theory) or host adipocytes (host replacement theory). Studies revealed a "fibroblast-like" mesenchymal cell within adipose tissue that was believed to be an immature adipocyte precursor or preadipocyte. Further characterization of the preadipocyte and its complete differentiation was accomplished using tissue-culture techniques. These investigations provide evidence of the dynamic nature of adipose tissue that strongly supports the cell survival theory and gives explanation to the unpredictable behavior of free fat autografts. Many conditions treated by plastic surgeons require soft-tissue augmentation. Autogenous adipose tissue is the most appropriate and natural replacement material. With new culturing techniques, preadipocytes in a single cell suspension may provide an injectable soft-tissue replacement. This subject appears ripe for investigation.