About 100 μg of 1, 2-dichloroethane was orally given to mice, or was incubated with mouse liver 9000×g supernatant fraction at 37°C for 60 min. Metabolites were extracted by dialyzing liver homogenate against acetone and separated by preparative thin-layer chromatography on an activated carbon plate with water as a development solvent. Each fraction of activated carbon scraped from the plate was monitored for ninhydrin-positive compounds by thin-layer chromatography on a precoated Silica gel G plate in a solvent of n-butanolacetic acid-water (4 : 1 : 1, v/v/v). The first fraction (origin) gave a significant ninhydrin-positive spot. After hydrolysis of this compound with 6 N hydrochloric acid, glutamic acid, glycine, and another product were found. The other product was identified as S-(β-hydroxyethyl) cysteine by mass spectrometry, amino acid analysis and thin-layer chromatography. The ninhydrin-positive metabolite formed from 1, 2-dichloroethane was thus identified as S-(β-hydroxyethyl) glutathione.