Chlorophytum comosum leaf extract is well-known to contain flavonoids. The extract has cytotoxic and cytostatic activity in normal animal cells. At concentrations of 15 mg/mL and above, the extract leads to 100% death of SPEV cells. The number of dead cells of the SPEV line generally increases with increasing extract concentration. The LC50 of Chlorophytum comosum extract was determined by probit analysis (LC50 = 7.24 mg/mL). With an increase in the concentration of the extract, a noticeable decrease in the proliferative activity of cells was observed. After 48 hours, the inhibition of proliferative activity of SPEV cells is more pronounced than after 24 hours. The percentage of SPEV cells that died under the action of Chlorophytum comosum extract becomes smaller with increasing exposure time.  The results of the analysis of the tumor mass at the end of the experiment fully correspond to the dynamics of its growth. The data obtained by us indicate the absence of the effect of Chlorophytum comosum extract against the transferable liver cancer of rats in an in vivo experiment.