BACKGROUND: Adipose-derived stem cells (ASCs) have positive effects in the wound healing process. OBJECTIVE: To clarify whether ASCs positively mitigate scar formation in the wound remodeling process. MATERIALS AND METHODS: Full-thickness skin defects were created on the dorsal skin of Yorkshire pigs. After the defects were transformed into early scars, ASCs were injected, and the same amount of phosphate buffered saline (PBS) was injected in the control group. Clinical and histologic examinations were performed. RESULTS: In the experimental group, the areas of scars were smaller than those of control groups. The color of scars was more similar to that of the surrounding normal tissue, and scar pliability was better. The number of mast cells decreased, and more-mature collagen arrangement was noted. In the early period of scar remodeling, the expression of transforming growth factor beta (TGF-β)3 and matrix metalloproteinase 1 (MMP1) was greater in the experimental group than in control group. In the late period, the level of alpha smooth muscle actin and tissue inhibitor of metalloproteinase 1 were dramatically less, although the level of MMP1 was lower in the experimental group than in control group. CONCLUSIONS: Local injection of ASCs decreases scar size and provides better color quality and scar pliability. It decreases the activity of mast cells and inhibits the action of TGF-β against fibroblasts and positively stimulates scar remodeling through greater expression of MMP molecules.