This study was carried out to investigate chemical ingredient of Amillaria tabescens. Methanol extract of Amillaria tabescens was analyzed by column chromatography, thin layer chromatography, HPLC, mass spectrophotometer. ATB201 was isolated by prep-HPLC from butyl alcohol fraction. From the physico-chemical data, including NMR, MS, the chemical structure of the compound was determined to be an uracil. (Fig. 1). The molecular weights of uracil was 112.