A study of the impurity emissions (300–1600 Å) in the Tandem Mirror Experiment (TMX) is described. Brightness measurements obtained with three absolutely calibrated monochromators, each viewing a separate section of TMX, showed that the dominant impurities were oxygen, nitrogen, carbon, and titanium. In the end cells, oxygen was the most abundant impurity with a concentration of ⪅2%; the neutral beams were a significant source of oxygen as in the 2XIIB experiment. In the central cell, the impurity concentrations were low: ⪅0.4% for each species. Emissions from carbon and oxygen in this region were reduced by titanium gettering of the vacuum chamber walls. Total radiative power losses due to impurities were <10% of the net trapped neutral beam power.