MicroRNAs are members of the family of noncoding small RNAs that regulate gene expression either by inhibiting mRNA translation or by promoting mRNA degradation at the posttranscriptional level. They play an important role in the differentiation of bone marrow-derived mesenchymal stem cells (MSCs) into neurons. However, the role of microRNAs in this process remains to be poorly understood. Studies have shown that Notch signaling is involved in regulating MSC differentiation. Here, we found that microRNA-9 could promote MSC neuronal differentiation. Using immunocytochemistry, western blotting, and reverse transcription-PCR analyses, we showed that the expression of the neural cell specific marker, microtubule-associated protein 2, increased during the process, while the expression of Notch-1 decreased. This study suggests that microRNA-9 might promote MSC neuronal differentiation by modulating the Notch signaling pathway.