Аннотация:The mechanical behavior of two-dimensional construction with negative Poisson`s ratio (auxetic construction) is experimentally studied. The concave hexagon with straight sides is often an element of structure in auxetic constructions. In this work the special design of a concave hexagon in which a part of straight elements is replaced with curvilinear elements is suggested. The sample was made by the laser cutting method of a non-auxetic polyethylene terephthalate (PET-a amorphous) planes. The transverse size of elements of hexagons is equal to sample thickness. The sample was subjected to a monotonous uniaxial tension till the last moment when it still remained plane. As a result of experimental data processing the tensile force - displacement diagram is calculated. Variability of Poisson`s ratio depending on engineering deformations is studied.