Transmission measurements have been carried out on thin films of lead selenide in the energy range 0.5-6 eV. The thicknesses varied from 180 to 550 Å. The index of refraction and the extinction coefficient were calculated by Kramers-Kronig analysis. These show a significant divergence from earlier published values. A splitting of the 4.5-eV absorption peak is observed at low temperatures, which is attributed to spin-orbit splitting in selenium.