Plastic pipes are being more widely used in various industries, as they combine both a rather light weight and quite high physical mechanical performance characteristics. The present article materials are devoted to the researches, relating to the determination of the various hydrocarbon compounds effect on some mechanical properties reduction degree of samples cut from HDPE pipes, represented by characteristic values of curves (strength - tensile strain) as an absorption result. In the course of the research, the gasoline presence in material structure of the pipe samples was noted to make the process unstable, and the curves representing a change in the characteristic values under study, depending on the immersion time in diesel fuel, tended to decrease throughout the entire immersion period. The experiments have shown that in the study of samples absorbing capacity a full saturation was obtained when immersed in diesel fuel and, despite large difference in absorbance values, the volume of absorbed hydrocarbons caused decline close to the studied characteristic values. Motor oils produced the most significant effect on the HDPE samples studied characteristics at the relatively low absorption values.