Absorbances of vapors generated by various SbI3 + Sb and SbI3 + It mixtures have been measured over the wavelength interval 210-510 nm. Concentrations calculated from SbI3(l) vapor pressures published by various authors are compared and used to derive molar absorptivities of SbI3(g). Values, at 10 nm intervals, have been assigned for the temperature range 390-850 K. Except for small irregularities at higher temperatures for SbI3 + Sb mixtures (WI?) and at the lowest temperatures for SbI3 + It mixtures (SbI5?) absorbance data can be satisfactorily explained assuming SbI3 to be the only compound of antimony in the vapor phase.