Abstract: Objective To study the neuroprotective effects of citicoline on apoptosis of neurons induced by 6-hydroxydopamine in vit ro and its mechanism.Methods The percentage of apoptosis and the expressions of Bax and Bcl-2 proteins in primary cultured neurons were detected by flow cytometer.Results As compared with 62hydroxydopamine group,1,0.1,0101 and 0.001 mmol/L citicoline group the apoptosis of neurons by 62hydroxydopamine-induced were decreased significantly,P<0.01;The expressions of Bax proteins were decreased and Bcl-2 proteins were increased,Bax/Bcl-2 ratio was lower than that of 62hydroxydopamine group,P<0.01.Conclusion The neurotoxic effect of 6-hydroxydopamine can be reduced by citicoline to decreese the percentage of neurons apoptosis.By downregulating the expressions of Bax proteins and upregulating expressions of Bcl-2 proteins,the apoptosis of neurons can be decreased and neurons were protected by citicoline.