Purpose: The purpose of this article is to present results of examining the hardness of the high density polyethylene with method of the cone.Design/methodology/approach: In the article a method of the cone was used for examining the hardness of the polythene of high density. Findings: The method of the cone it is possible to examine small samples and he allows for more exact measurements than different methods of examining the hardness.Research limitations/implications: The methods presented in this paper differ in the size and the shape of the indenter. The choice of the method of the measurement of the hardness in case of crystalline polymers is difficult since none of known methods has the right measuring resolution. The method of the cone is solving in the case of examining polymers. The method of the cone isn’t limited only to polymer materialsPractical implications: Presented method can be applied for other materials in the future.Originality/value: The expressed method can be applied in the future for developing the research on the hardness of polymers.