We report on an experimental study of the polarization properties of large mode-area photonic crystal fibers (PCFs). We find that such fibers may exhibit very low birefringence and polarization-mode dispersion (PMD) indicating a highly symmetrical hole structure over a long length. Moreover, the influence of temperature on the polarization-mode dispersion is investigated. The results show that it is possible to fabricate photonic crystal fibers with polarization-mode dispersion, which is nearly insensitive to changes in temperature.