OBJECTIVE To investigate the regulatory mechanism of micro ribonucleic acid (miR)-146a in osteogenic differentiation and proliferation of bone marrow stromal cells (BMSCs) in traumatic femoral head necrosis. METHODS Femoral neck fracture patients undergoing surgery were divided into necrosis group and non-necrosis group. The expression level of miR-146a in BMSCs isolated from these patients was detected via quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The clinical correlation of miR-146a with BMSCs in traumatic femoral head necrosis was explored. The regulatory effects of miR-146a on osteogenic differentiation and proliferation of BMSCs in traumatic femoral head necrosis were detected. Moreover, the cell proliferation was analyzed via cell counting kit-8 (CCK-8) assay. The deposition of calcium on the cell surface was detected via alizarin red staining to evaluate the osteogenic differentiation. The messenger RNA (mRNA) expressions of osteogenesis-specific genes, alkaline phosphatase (ALP), and osteocalcin (Ocn) in BMSCs undergoing osteogenic differentiation were detected via qRT-PCR. RESULTS Expression level of miR-146a in BMSCs of necrosis group was significantly lower than that in non-necrosis group, and the difference was statistically significant (p<0.01). CCK-8 assay revealed that the proliferation of BMSCs was significantly enhanced in miR-146a-mimic group compared with that in miR-NC group, while it significantly declined in miR-146a-inhibitor group compared with that in miR-NC group. The results of alizarin red staining showed that the deposition of calcium obviously increased in miR-146a-mimic group compared with that in miR-NC group, indicating that the osteogenic differentiation ability is significantly enhanced, while it markedly decreased in miR-146a-inhibitor group compared with that in miR-NC group. The detection of osteogenesis-specific genes via qRT-PCR manifested that the mRNA expressions of ALP and Ocn remarkably increased in miR-146a-mimic group compared with those in miR-NC group, and there were statistically significant differences (p<0.05). The mRNA expressions of ALP and Ocn remarkably decreased in miR-146a-inhibitor group compared with those in miR-NC group, and there were statistically significant differences (p<0.05), suggesting the inhibited osteogenic differentiation ability. CONCLUSIONS We showed that miR-146a regulates the osteogenic differentiation and proliferation of BMSCs in traumatic femoral head necrosis.