Objectives: The aim of the present study was to investigate the effect of proinflammatory cytokine TNFα and its decoy TNFR1 on proliferation and osteogenic differentiation of gingival mesenchymal stem/progenitor cells (G-MSCs).Methods: Human G-MSCs were isolated, cultured and magnetically sorted using Stro1 antibodies. Flow cytometric analysis was carried out for the expression of CD14, CD34, CD45, CD73, CD90, CD105, CD146 (Miltenyi-Biotec) and STRO-1 surface markers. Trilineage differentiation and colony-forming units (CFUs) assay were performed. G-MSCs were primed for 72 hours using 1ng/ml TNFα (group 1), 1ng/ml TNFα and 10ng/ml TNFR1 (group2) and 10ng/ml TNFR1 (group3) while group 4 was unprimed. All four groups were subsequently cultured for two weeks in osteogenic inductive medium. Alzarin red, MTT test and the gene expression of Collagen I, ALP, osteonectin were measured using RT-PCR and normalized to that of GAPDH. Statistical analysis was performed by repeated measures ANOVA (p≤0.05).Results: G-MSCs showed all the criteria defined for MSCs. After two weeks of osteogenic induction, the four groups expressed calcified nodules, when stained with Alzarin red. Group 2 (Mean=107.9%±10.2) showed significantly higher proliferation than group 1 (Mean=97.8% ±12.8) (p= 0.014) by MTT test. There were no statistically significant differences in the gene expression profile among the groups.Conclusion: The combination of TNFα and TNFR1 increased the proliferation of G-MSCs compared to TNFα alone. TNFα and TNFR1 had no effect on the osteogenic differentiation potential of G-MSCs.