Interleukin-HA (IL-17A) enhances the osteogenic differentiation and increases osteoprotegerin (OPG)/receptor activator of NF-KB ligand (RANKL) expression of the stem cells. from human deciduous teeth (SHED). The OPG/RANKL system is essential in bone metabolism where RANKL augments bone resorption whereas OPG favours osteogenesis. This study investigates the effects of IL-17A on the osteogenic differentiation and its effect on the RANKUOPG signalling pathway. IL-17A enhanced proliferation and alkaline phosphatase activity in SHED in a dose-dependent manner. IL-17A also increased calcium deposition which indicated mineralization activity. Moreover, the expressions of ALP, COL 1A1, RUNX2, OCN, OPN and OPG were significantly up-regulated when treated with IL-17A In contrast, IL-17A downregulated RANKL expression in SHED. Interestingly, the OPG/RANKL ratio was significantly higher in IL-17A-treated groups. We also demonstrated that IL-17A activated MAPK signalling pathway by significant up-regulation of upstream activators and downstream targets of ERK, P38 and JNK pathway. We conclude that IL-17A demonstrates osteo-stimulating effects; thus suggests the use of IL-17A in bone substitutes to promote bone regeneration.