A precise relative optical density spectrum of the macular pigment, based upon its dichroic properties, was determined. The spectrum proved essentially identical to that of liposome-bound zeaxanthin and lutein, a system duplicating the macular pigment and its environment. Substantial agreement was also found with the spectra of Wyszecki and Stiles (1982, Color science: Concepts and methods, quantitative data and formulae. New York: Wiley) and Vos (1972, Institute for Perception, RVO-TNO, IZF 1972-17, Soesterberg, The Netherlands), and the latter is recommended as a standard. For 7 subjects, the pigment density spectrum derived from foveal and extra-foveal sensitivities was compared with the dichroism-based spectrum. Results indicated that the pigment is described by a common distribution of molecular orientations for all subjects.