OBJECTIVES: Oestrogen receptor (ER) is a common nucleus receptor that is essential for the regulation of cell growth, proliferation and differentiation. This study was to examine whether ERα can affect the proliferation and odonto/osteogenic differentiation of stem cells from apical papilla (SCAPs). MATERIALS AND METHODS: Stem cells from apical papillas were isolated, purified and then transfected with ERα lentiviruses. The proliferation capacity was investigated by cell counting kit-8 (CCK-8) assay and flow cytometry. The odonto/osteogenic differentiation ability was analysed by alkaline phosphatase (ALP) activity, alizarin red staining, western blot assay (WB) and real-time RT-PCR. MAPK pathway and its downstream transcriptional factors were explored by WB assay. RESULTS: As indicated by CCK-8 assay and flow cytometry, ERα had no significant effect on the proliferation of SCAPs. When ERα was overexpressed, the ALP activity and the formation of calcified nodules were significantly enhanced in SCAPs. Moreover, the odonto/osteogenic markers (DMP1/DMP1, DSPP/DSP, RUNX2/RUNX2, OCN/OCN) in SCAPs were significantly up-regulated at both mRNA and protein levels. On the contrary, the odonto/osteogenic differentiation ability of SCAPs was remarkably inhibited after suppression of ERα. Mechanistically, the protein levels of phosphorylated ERK and JNK significantly increased after ERα overexpression. Moreover, some downstream transcriptional factors of MAPK pathway were simultaneously activated by ERα overexpression. CONCLUSIONS: Together, the data accumulated here indicated that ERα can enhance the odonto/osteogenic differentiation of SCAPs via ERK and JNK MAPK pathways.