Fat injection is being used for the correction of various soft-tissue defects. In this study, the manner of fat injection yielding the greatest transplant viability was examined. Autologous fat was obtained from the inguinal area of rats and subsequently reinjected to the nuchal region, an area naturally poor in subcutaneous fat. Before injection, the fat was processed by one or more of the following methods: suture of the recipient area, repeated washing to remove residual blood, and addition of insulin. Transplant status was evaluated by both macroscopic and microscopic examination of the recipient sites 2 weeks and 12 weeks after the injection. The results demonstrated that the injected fat remained in part as viable new fatty tissue in the nuchal area. No statistically significant improvement in the viability of the injection fat was noticed at 2 weeks and 12 weeks after its processing by the different methods just described. Significant positive correlation was demonstrated between the volume of the injected fat and the size of the bulging at the injection area only 2 weeks after the injection.