We report a detailed temperature dependent study of polarized piezoreflectance (PzR) for two GaInP epilayers that exhibit different degrees of ordering in the range between 25 and 500 K. The polarized PzR measurements showed anisotropic character along the [110] and [1 0] directions for the ordered sample. The PzR spectra were fitted using the first derivative of a Lorentzian line shape functional form. The direct band-to-band, crystal-field splitting to band and spin-orbit splitting to band transition energies which are denoted as E ₀ , E ₀ + _c and E ₀ + _s respectively, at various temperatures, were accurately determined. The temperature dependences of these near band-edge critical point transition energies were analysed by the Varshni expression and an expression containing the Bose-Einstein occupation factor for phonons. The parameters that describe the temperature variation of the transition energies are evaluated and discussed.