OBJECTIVE To study the effect of 3`-azido-3`-deoxythymidine (AZT) on telomerase activity and the proliferation of ovarian cancer cells in vitro. METHODS Telomerase activity was detected by enzyme linked immunosorbent assay (ELISA) in treated and untreated HO-8910 cells by AZT. The detection of cell viability was performed with 3-(4,5-dimethylthiazol-2-yl)-2,5-Diphenyl tetrazolium bromide (MTT) assay and the ultrastructure of the cells was observed by electron microscopy. The apoptotic rate of the cells was measured by flow cytometry. RESULTS AZT significantly inhibited telomerase activity of HO-8910 cells, and the effect was both time- and dose-dependent. The HO-8910 cells treated at different concentrations of AZT showed a significant reduction of cell viability and morphological changes of apoptosis. The apoptotic peak was detected in the AZT treated cells and the apoptotic rate was 14.2%. CONCLUSIONS AZT can effectively inhibit both telomerase activity and proliferation of human ovarian cancer HO-8910 cells in vitro, suggesting that AZT may be used in the clinic treatment of ovarian cancer.