Dimethylacetamide is widely used in the production of plastics, resins, synthetic fibers, and gums and in purification and crystallization processes. Inhalation of the vapor or skin absorption of the liquid of dimethylacetamide(DMAC) can cause liver damage. Toxic hepatitis possibly attributable to DMAC exposure occurred in seven works among 178 employees who had worked on a new spandex-fiber production line. A large amount of DMAC is used as a spinning solvent for synthetic fibers in the factory. The patients were aged 23-47 years old and composed of five males and two females. They were involved in the process of polymerization(1 patient), spinning(1), take-up(4) and packaging(1). The mean duration of exposure was 10 weeks. They experienced fatigue, dizziness and jaundice. The patients showed elavated total bilirubin, alanine aminotransferase(ALT), and aspartate aminotransferase(AST) levels. The serologic test for viral hepatitis A, B and C were negative, as were the abdominal ultrasonographic scans. Based on the presumptive diagnosis of DMAC-induced toxic hepatitis, they were removed from the workplaces. One or two months after removal from the work, the transaminase levels returned to normal. The patients had no history of significant alcohol use, blood transfusion, recent medication, and drug abuse. As a result, authors could not find any attributable cause of toxic hepatitis but the toxicity by DMAC exposure.