Objective To observe the electrophysiological characteristics of the inward current of cardiomyocyte-like cells derived from rat bone marrow mesenchymal stem cells (MSCs). Methods Bone marrow specimens was extracted from SD rats aged 1 month. MSCs were isolated by gradient centrifugation and obtained by adherence culture. The second-passage MSCs were treated with 10 ?mol/L 5-azacytidine and incubated for 24 h. After 4 weeks, cardiomyocyte-like cells were identified by immunocytochemical staining technique, then used to detect the inward current with the whole-cell patch-clamp technique, which results were compared with the normal cardiomyocytes and the MSCs without induction. Results Some cardiomyocyte-like cells were stained positive for troponin T, and the quickly activated and inactivated inward currents were elicited 4 weeks after 5-aza cytidine treatment. The inward currents of cardiomyocyte-like cells recorded in the same square pulse were weaker than that of the normal cardiomyocytes, and the I-V curve of cardiomyocyte-like cells was right-shifted. Conclusion After treated with 5-azacytidine, MSCs differentiate into cardiomyocyte-like cells which express the excitable inward current.