Objective To compare the expression changes of neuropeptide Y (NPY) receptor Y1 in different stages of osteoblast differentiation of rat bone marrow mesenchymal stem cells (BMSCs).Methods The rBMSCs were isolated in vitro from Sprague-Dawley (SD) rats using whole bone marrow adherence method and cultured. Then, the rBMSCs were divided into osteoblast-induced group and noninduced group. In different periods of culture at 1, 2 and 3 weeks, identification of the osteoblasts was performed by using immunocytochemistry and Western blot. Expressions of mRNA and protein of Y1 receptor were detected by real time reserve transcriptase-polymerase chain reaction (RT-PCR) and Western blot. Results RT-PCR demonstrated that osteoblast-induced group had a lower expression of Y1 receptor than non-induced group at the same time point and the expression of Y1 receptor was increased in a time-dependent manner in both groups. Western blot demonstrated higher expression of Y1 receptor in osteoblast-induced group compared with non-induced group at the same time point and a decreased expression of Y1 receptor in a time-dependent manner in both groups. Conclusions During the process of osteoblastic differentiation of rat BMSCs, the expressions of mRNA and protein of NPY Y1 receptor show different trends, when NPY may mediate the inhibition of osteoblastic differentiation of BMSCs through Y1 receptor pathway.