Prompt treatment in tumor-associated encephalopathy may prolong survival. We describe a 69-year-old male patient who was presented with fulminant hepatic failure, secondary to small-cell lung carcinoma with rapidly progressing encephalopathy. Both symptoms remitted following chemotherapy, suggesting swift diagnosis and administration of chemotherapy to be effective in treatment of fulminant hepatic failure and encephalopathy. Prompt treatment in tumor-associated encephalopathy may prolong survival. We describe a 69-year-old male patient who was presented with fulminant hepatic failure, secondary to small-cell lung carcinoma with rapidly progressing encephalopathy. Both symptoms remitted following chemotherapy, suggesting swift diagnosis and administration of chemotherapy to be effective in treatment of fulminant hepatic failure and encephalopathy.