Purpose: With the recent recognition of the importance of soft-tissue fillers, fat grafting has been assumed an increasingly important role as both an adjunctive and a primary procedure in aesthetic and reconstructive surgery. The main problem in achieving long-term soft-tissue augmentation is partial absorption of the injected fat and hence the need for overcorrection and re-injection. The purpose of this study is to improve the viability of the injected fat by the use of Lipo-PGE1. Methods: Human adipose tissue, obtained by suctionassisted lipectomy, was re -injected into the subcutaneous layer in the scalp of ICR mice. Lipo-PGE1 ($0.5{mu}g$/kg) was injected intravenously in experimental group for 7 days from the operation day and saline was injected in control group. There were 5 animals in each group. The animals were euthanized 4 weeks after the procedure. Graft weight and volume were measured and histologic evaluation was performed. Result: Histologic analysis demonstrated significantly less cyst formation and less inflammatory reaction in the group treated with Lipo-PGE1. No significant difference was found between the groups regarding graft volume or the other histologic parameters investigated. Significant differences were demonstrated in microvascular density count. Conclusion: Less cyst formation, less inflammation, more angiogenesis indicating improved quality of the injected fat can be obtained by the addition of Lipo-PGE1. Further studies of various dosages of Lipo-PGE1 and their long-term effect are required before these encouraging results could be applied clinically.