Background: There are many collagen stimulating fillers, including Calcium Hydroxyapatite(CaHA), Polycaprolactone (PCL), and Poly-L-Lactic acid(PLLA). Other materials has been tested for collagen stimulating fillers. Polydioxanone (PDO) is used as absorbable thread lifting material due to its collagen forming effect, recently. PDO, in powdered form, is expected to be a good material for collagen producing fillers. Objectives: To evaluate collagen producing effect of powdered PDO injection compared with PLLA injection in murine model Methods: Powdered PDO mixed with sodium carboxymethylcellulose(CMC), PLLA, and phosphatebuffered saline were injected on dorsal skin of 8-week-old rat. Tissue samples were obtained at 1, 2, 12 weeks after the procedure for histopathologic review and Real-time PCR for quantification of collagen and tissue growth factors. Results: Both PLLA and powdered PDO injection induced granulomatous reaction. Collagen type 1, Collagen type 3, TGF-β1, TGF-β2, and TGF-β3 showed increases at 2 weeks after injection but showed decreases at 12 weeks after injection in both powdered PDO and PLLA injection. Conclusion: Our result suggested that powdered PDO injection induces collagen formation effectively compared with PLLA injection. Therefore it can be a good option for collagen forming treatment.