Abstract: Objective 　To investigate the effect s of c-myc ASODN on MCF-7 cells growth and the expression of hTERT gene in MCF-7 cells. Methods 　After transfecting c-myc SODN and ASODN to MCF-7 cells, we measured the proliferation, apoptosis rates and the expression of hTERT mRNA respectively by MTT method, flow cytomet ry analysis and RT-PCR. Results 　When c-myc ASODN affected MCR-7 cells at 24h, cells growth was inhibited significantly ( P < 0. 05) with hTERT gene expression of MCF-7 cells descending significantly ( P < 0. 01) . The apoptosis rates of the ASODN2t reated cells rised significantly at 48h. The described effect s of suppression on cells rised with time increasing. Conclusion 　c-myc ASODN can effectively inhibit the MCF-7 cells growth, induce apoptosis, and down-regulate hTERT gene expression in MCF27 cell. The effects correlated with time to a degree.