Abstract. Serum magnesium (Mg) levels are closely controlled through a variety of Mg transporters and ionic channels during physiological conditions. These levels have been shown to increase during exercise. However, the effect of Mg transporter expression during exercise remains to be determined. The purpose of this study was to examine the gene expression of SLC41A1, a Na + /Mg 2+ exchanger, during exercise. In the present study, male C57BL/6JNarl mice (n=16, 8 weeks old) were subjected to 3 h forced exercise on a treadmill. The mice in the control and Mg groups were injected with saline and Mg (MgSO 4 , 90 mg/kg, intraperitoneal), respectively. Blood samples were obtained at three time points: prior to, following and 24 h after exercise. The gene expression levels of SLC41A1 were significantly downregulated to 23.6±4.6 and 12.6±10.2% following exercise in the control and Mg groups, respectively. The expression levels returned to the basal levels 24 h after exercise in the two groups and there was no significant difference found between the two groups. The downregulated role of SLC41A1 expression and its interaction with the Mg status in exercise requires further investigation.