The results of the investigation of the mechanical properties of polyethylene (PE) blends with small (<3 wt %) additions of thermotropic liquid-crystalline polymers (LCPs) are reported. PE/LCP compositions with various LCP weight contents were obtained by thermoplastic mixing in a two-stage process. Short-term and long-term mechanical behavior of various PE/LCP compositions were analyzed. Data on the influence of LCP addition on the tensile elastic modulus [or Young's modulus (E)], stress at yield (sigma(Y)), stress at break (sigma(B)), strain at yield, strain at break, and deformation at long-term (1000-h) tensile creep were obtained. The experimental results of the investigation show that even small additions of LCP allowed considerable increases in E, sigma(Y), sigma(B), and creep resistance of PE. To support the experimental data, we mathematically analyzed the elastic properties of the materials by taking into account the effect of self-reinforcement due to the formation of extended LCP inclusions. The results of the theoretical analysis testify that LCP inclusions in the continuous PE matrix were elongated 5-10 times because of their orientation during the manufacturing of the test specimens. Analytical descriptions of the creep of the PE/LCP blends are also presented. It is demonstrated that the creep behavior of the PE/LCP blends could be sufficiently well described by power law. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3564-3568, 2011