There is no specific treatment for dengue-associated fulminant liver failure. We report a child with dengue-associated fulminant liver failure who was treated successfully with intravenous N-acetylcysteine. A 6-year-old boy was diagnosed with dengue-associated fulminant liver failure. After administration of intravenous N-acetylcysteine, a rapid decrease in liver transaminases and normalization of coagulation profile was observed followed by clinical improvement and favourable outcome despite factors associated with poor prognosis. The use of intravenous N-acetylcysteine is safe and efficient in the treatment of dengue-associated fulminant liver failure, especially in centres when liver transplantation is not readily available.