In this article I review the present state of knowledge about adipose tissue as it is relevant to the practical purposes of plastic surgery. Fat cells are normal constituents of loose connective tissue. Large numbers of fat cells organized into lobules are classified as adipose tissue. Adipose tissue is a special form of reticular connective tissue. The lobules are both morphologically and angiologically independent units. They are seen as well-vascularized structures supplied with blood through a pedicle. Severance of the lobule normally results in necrosis. The subcutaneous fat layer derives from the "primitive organs" identifiable in the hypodermis from the fourth fetal month onward. The primitive organs are the basis for individual fat lobules. The development of adipose tissue continues until physical growth is complete. The disposition of the subcutis to develop adipose tissue shows great variation in different regions of the body. The in-situ mechanical resistance of adipose tissue is provided by the supporting structures. The development, structural characteristics, and physiology of adipose tissue can provide an explanation for many of the observations plastic surgeons have made on this tissue. The processes involved in healing, grafting, and reduction of adipose tissue are analyzed and considered in relation to the clinical picture.