Abstract： Objective To observe hematoxylin's cytocidal and apoptosis-inducing effects on human urinary cancer cell-T24,and its cytocidal mechanism to the target cell.Methods Target cells were incubated in the medium 1640 for 24h,which contained hematoxylin in dosage of zero(blank),12.5,25,50,100,200μg/ml,respectively;under inverted microscopy to observe target cells'morphologic change,and then harvest them;by trypan blue tmpochrome method to determine hematoxylin's cytocidal activity to the target cells;by flow cytomelry to detect the effects of hematoxylin in its different levels on target cells'apoptosis.Results The control group(without hematoxylin)showed their target cells in a fusiform adherent growth,plump,close-arranged,and with a good transparence.With the addition and increment of hematoxylin,target cells turned round,not adherent,pyknotic,with a bad transparence,as well as chromatin condensation,the cells clumped.Cell death rate of control group was(2.63±0.29)%,with the increased dosage of hematoxylin the cell death rate of test groups was(10.00±4.82)%,(21.88±3.42)%,(76.41±4.82)%,(92.27±6.54)%,and(96.34±8.70)%respectively.Flow cytometry showed cell apoptosis rate in control group was 0.47%(occurred spontaneously),but hematoxylin in dose of 50μg/ml made the apoptosis rate increased markedly,to 43.1 8%,dead cell rate 48.47%,and survival cell rate 8.35%.With the increased hematoxylin dose,cell apoptosis rate decreased gradually,while dead cell rate increased.Conclusion Hematoxylin can inhibit the target cell by two routes:to induce apoptose or kill it.In a lower dose it is able to induce target cell to apeptose;hematoxylin in a dose over 100μg/ml can directly kill the target cell.Making this trial for checking the cell's morphologic changes benefits determining the optimal dosage level and optimal acting duration for the apoptosis induction.