In order to improve the sensitivity of the current assay methods of selenium in dried-yeast preparations, atomic absorption spectrophotometry (AAS), high performance liquid chromatography (HPLC) and UV-Vis spectrophotometry were employed. The sample was prepared with the digestion by acid mixture of hydrochloric acid, nitric acid and perchloric acid after elimination of ether-soluble substances. The range of quantitation of selenium was $1.0{sim}6.0;{mu}g/ml$ by UV-Vis spectrophotometry, $5.0{sim}20.0;{mu}g/ml$ by HPLC and $0.03{sim}0.10;{mu}g/ml$ by AAS.