The optical properties of AuMn alloy systems have been measured by a polarimetric technique through an energy range 0.8 eV to 4 eV. The Mn impurities are found to increase the classical collision frequency of the intraband absorption. The onset of direct interband transitions shifts slightly to higher energies with increasing Mn concentration in approximate agreement with Friedel's theory. Extra absorption bands are found to be present in the alloys compared to the pure noble metals, and these are interpreted as arising from spin split virtual levels. The total spin splitting of the impurity levels is about 4.8 eV for AgMn and about 4.6 eV for AuMn.