Objective; To investigate the effect of NDGA, the lipoxygenase inhibitor, on colon cancer cell line HT-29 in vitro from the aspects of cell growth inhibition, cell apoptosis and its impact on the expression of telomerase. Methods: We applied respectively i) MTT to draw the growth curve. ii) inverted phase contrast microscope to observe morphologic change of cells, iii) scanning electron microscope to observe changes of cell's ultra-microstructure and apoptotic body. iv) RT-PCR to detect the changes of the expression of human telomerase reverse transeriptase (hTERT). Results: Different concentrations of NDGA were used to dispose cancer cells separately, with the rise of the drugis concentration, the form of cells became round, the volume waned, cells abscised from the inner surface of the bottle. and growth inhibition became increasing abvious. Also through scaming electron microscope, apoptic bodies could be found colon cancer cell line HT-29 showed positive expression of hTERTmRNA, which became weaker following the rising of the drugs concentration. Conclusions: NDGA which, displays the relying effect of doses, can inhibit the growth of colon cancer cell line HT-29 and induce its apoptosis, telomerase plays an active role in this course.