Abstract: The invention relates to biocidal polymers based on guanidine salts characterized in that they are representatives of a number of polyoxyalkylene guanidines and their salts and are a product of a polycondensation of guanidine salts with diamines which include two amino groups and polyoxyalkylene chains therebetween. In addition to a high bactericidity, these new polymer products are provided with a relatively low toxicity, an increased hydrophily, a quick and complete dilution in water, increased values of relative molar mass, and distinct characteristics of polymer surface active substances.