A set of parameters for the temperature dependence of the direct band gap of InP has been determined by fitting the excitonic recombination energy in the photoluminescence (PL) spectra between 2 and 250 K. We have used high-quality InP samples grown by chemical beam epitaxy. The superfluid-helium temperature PL spectra are characterized by strong excitonic transitions (the excited state n = 2 of the exciton is observed too) from which we have determined the binding energy of the exciton (E(b) = 5.3 meV) and the band-gap energy (E(g) = 1.4239 eV at 1.3 K). The variable-temperature PL spectra are characterized by excitonic transitions for temperatures as high as 250 K. The expression E(g)(T) = 1.4539 - 0.0359(1 + 2/ {exp[209/T (K)] - 1}) eV, which extrapolates to E(g) = 1.347 eV at 300 K, is proposed for the temperature dependence of the InP band gap over the temperature range 0-300 K.