The hemolytic activity of a collection of 63 steroid saponins was determined. The correlations between these structures and their hemolytic and cytotoxic activities are discussed. It has been demonstrated that the hemolytic activity of steroid saponins is highly dependent on their structures, that is, the sugar length, the sugar linkage, the substitutes on the sugar, as well as the aglycone. It has also been disclosed that the hemolytic activity and cytotoxicity of steroid saponins are not correlated. These results suggest that steroid saponins execute hemolysis and cytotoxic activity in different mechanisms, and encourage to develop steroid saponins into potent antitumor agents devoid of the detrimental effect of hemolysis.