A 54-year-old woman was admitted to our clinic with frequent convulsions. Subsequently she developed a toxic look, rigidity, confusion and severe encephalopathy. Salmonella typhii was isolated from the blood cultures and she was diagnosed with Salmonella encephalopathy. The prominent electrophysiological finding was the frontal intermittent rhythmic delta activity (FIRDA) in electroencephalograph (EEG). After treatment EEG revealed normal activity. The presence of FIRDA is not a specific finding but this kind of EEG change has not been reported before. Diffuse encephalopathy due to endotoxins might be the reason. We propose that S. typhii encephalopathy was the cause of FIRDA which is a sign of diffuse encephalopathy.