Objective To study the expression of gamma-aminobutyrie acid type A receptor (GABAAR) α1 subunit following convulsion induced by magnesium-flee medium in developing cortical neurons. Methods Rat embryo cortical neurons cultured for 6 days were cultured for 3 h in normal or magnesium-flee extracellular fluid, followed by further culture in DMEM. At 1, 7 and 12 days after magnesium-free treatment, RT-PCR, immunocytochemical staining, and flow cytometry were performed to detect the expression of GABAAR α1 subunit. Results Compared with that in the control group, GABAAR α1-positive cells in the magnesium-free group decreased significantly at 12 days (P<0.05). Immunoeytochemical staining showed a significant decrease of accumulated optical density (AOD) of GABAAR α1 subunit in the magnesium-free group at 7 and 12 days as compared with that in the control group (P<0.05); the mRNA expression of GABAAR α1 subunit in the magnesium-free group decreased significantly at 1 day compared to that in the control group (P<0.05). Conclusion The expression of GABAAR α1 subunit is altered following convulsion induced by magnesium-free medium in developing cortical neurons.