Background: THAP11 is a recently discovered pluripotency factor and described as an important gene that involved in embryonic stem cells self-renewal and embryo development, which works independently with other known pluripotency factors. We aimed to overexpressed the THAP11 gene in primary fibroblast cells to determine the effects of the THAP11 on these cells. Materials and Methods: The THAP11 gene was amplified using PCR followed by ligation into pCDH vector and lentiviral particle production in HEK293T cells by using psPAX2 and pMD2.G helper vectors. The human fibroblast cells were transduced using viral particles and after confirmation overexpression, the key pluripotency factors were estimated using real-time PCR and changes in proliferation rate was measured by the 3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyltetrazolium bromide (MTT) test. Results: The overexpression of THAP11 in fibroblast cells leads to increase the expression level of Sox2, Oct4, Nanog and Klf4 as key pluripotency genes and a decrease in proliferation rate according to MTT results. Conclusion: Our results confirm that we are faced with a molecule with double features, which could be involved in pluripotency and proliferation suppressor simultaneously. It seems that the roles of THAP11 in pluripotency are so complex and attributed to other regulatory molecules. [GMJ.2019;8:e1308]