Abstract: Metformin is a commonly used anti-diabetic chemical. Underlying mechanisms are not fully understood if its actions are directed towards insulin receptors downstream events. In vitro expansion and proliferation of fibroblast stem cells depend on the presence of certain environmental factors among which is oxygen. The major goal of this study was to investigate the effect of Metformin on the proliferation of skin derived stem cells in case of normoxia and hypoxia. The results suggest that fibroblast stem cells proliferation is largely affected by high dose (100 μg mL-1) of Metformin. Obtained data indicated that Metformin significantly inhibited cell survival by a dose-dependent manner in three doses: Metformin 10, 50 and Metformin 100 μg mL-1. Metformin decreased cell survival in dose 100 μg mL-1 more than other two doses, also the experiment pointed to a significant effect of short-term low oxygen (5% O2) treatment on fibroblast proliferation combined with data that fibroblast exposed to 20% oxygen tension exhibited enhanced fibroblast proliferation and viability. By MTT assay results, it has been noticed that no significant changes in the proliferation of fibroblast during the cell culturing both on the first and the third day after metformin administration.