Acetanilide is a High Production Volume Chemical, which is produced about 2,300 tons/year in Korea as of 1998 survey. Most is used as an intermediate for synthesis of pharmaceuticals and dyes. The chemical is one of seven chemicals, which are under the frame of OECD SIDS program sponsored by National Institute of Environmental Research of Korea. Regarding the information on the environmental fate. bioconcentration is one of important factor to estimate the environmental tranfer. However, measurement of bioconcentration needs high expense and time. For this reason, OECD recommends to use BCFWIN model to estimate bioconcentration of organic chemicals, BCFWIN estimates the bioconcentration factor (BCF) of an organic compound using the log octanol-water partition coefficient (Kow) of the compound. Structures are entered into BCFWIN through SMITES (Simplified Molecular Input Line Entry System) notations. The BCFWIN method classifies a compound as either ionic or non-ionic. ionic compounds include carboxylic acids, sulfonic acids and salts of sulfonic acids, and charged nitrogen compounds (nitrogen with a + 5 valence such as quaternary ammonium compounds). All other compounds are classified as non-ionic. In this study, bioaccumulation of acetanilide was estimated using BCFWIN model based on SMIIES notation, chemical name data and partition coefficient as one of environmental fate/distribution of the chemical elements.