To gain an understanding of the toxicity of antimicrobial polymers to human cells,their hemolytic action was investigated using human red blood cells(RBCs).We examined the hemolysis induced by cationic amphiphilic methacrylate random copolymers,which have amino ethyl sidechains as cationic units and either butyl or methyl methacrylate as hydrophobic units.The polymer with 30 mol% butyl sidechains(B30) displayed higher hemolytic toxicity than the polymer with 59 mol% methyl sidechains(M59).B30 also induced faster release of hemoglobin from RBCs than M59.A new theoretical model is proposed based on two consecutive steps to form active polymer species on the RBC membranes,which are associated to RBC lysis.This model takes the all-or-none release of hemoglobin by the rupture of RBCs into account,providing new insight into the polymer-induced hemolysis regarding how individual or collective cells respond to the polymers. To gain an understanding of the toxicity of antimicrobial polymers to human cells, their hemolytic action was investigated using human red blood cells (RBCs) .We examined the hemolysis induced by cationic amphiphilic methacrylate random copolymers, which have aminoethyl sidechains as cationic units and either butyl or methyl methacrylate as hydrophobic units. The polymer with 30 mol% of butyl sidechains (B30) displayed higher hemolytic toxicity than the polymer with 59 mol% of methyl sidechains (M59). B30 also induced faster release of hemoglobin from RBCs than M59.A new theoretical model is proposed based on two consecutive steps to form active polymer species on the RBCs into account, providing proof of the hemoglobin by the rupture of RBCs into account, providing new insight into the polymer-induced hemolysis regarding individual or collective cells respond to the polymers.