Radioactive luminous compounds represent a significant potential source of radiation exposure to both industrial workers and the general public. Luminous compounds with tritium as the activating agent are in relatively widespread usage in the painting of watch and instrument dials and in the production of radio-luminescent light sources. It is therefore desirable to have accurate information regarding the degree of uptake and the metabolic behavior of tritiated luminous compounds in general, and comparative data regarding the specific tritiated compounds now in use. In the present study the gastrointestinal(GI) tract and cutaneous absorptions of four commercially available tritiated luminous compounds were investigated. The cat was chosen as the experimental animal for studies of GI tract absorption because of the relative similarity of its GI system with that of the human. Cutaneous absorption of the tritiated compounds was studied in the rat.