Objective: To investigate the expression changes of EphB4/ephrinB2 in normal bone marrow derived mesenchymal stem cells (MSCs) co-cultured with myeloma cell lines U266 or RPMI8226. Methods: Bone marrow MSCs from normal subjects were co-cultured with U266 or RPMI8226 by transwell for 7 days to 12 days. The mRNA expression levels of EphB4/ephrinB2 in MSCs were detected by real time quantitative PCR (RT-PCR) at point times and the protein levels of EphB4/ephrinB2 were analyzed by immunocytochemistry. Results: No evident morphologic and proliferative alterations could be observed in MSCs after co-culture with U266 or RPMI8226. The mean mRNA expression levels of EphB4/ephrinB2 were down-regulated in MSCs after co-culture with U266 or RPMI8226 as compared with controls. There was a significant difference on the point time of the 7th day’ point(P < 0.05) except EphB4 of MSCs co-cultured with RPMI8226 and no significant difference on the 12 day’ point(P > 0.05) between co-cultured MSCs and the controls. The protein levels of EphB4/ephrinB2 were also reduced in co-cultured MSCs. Conclusion: The communication between bone marrow MSCs and myeloma cells induced dysregulation of EphB4/ephrinB2,which may contribute to uncoupling of bone remodeling in myeloma bone disease.