The kinetic and concentration dependences of erythrocyte vesiculation and hemolysis induced by sodium dodecyl sulfate were studied. The similarity of the slopes of the dose dependence of the SDS-induced vesiculation and slow hemolysis rates in the double logarithmic coordinates suggested a close relation between the processes of vesiculation and pore formation for slow hemolysis by the detergent. Further evidence of the competitive nature of the detergent-induced vesiculation and fast hemolysis by sodium dodecyl sulfate was obtained. The phenomenon of partial hemolysis proceeding at a rate comparable to that of cell vesiculation is explained in terms of the competition between hemolysis and vesiculation, without resorting to erythrocyte heterogeneity. New vesicular-competitive hemolysis is described. Based on it, the action of different hemolysis-inducing agents is analysed.