Neuropsychological dysfunction may precede, occur simultaneously with, or follow the icteric phase of viral hepatitis. Encephalitic and meningitic involvement appears to precede the onset of clinical hepatitis while the tremor syndrome usually follows the onset of illness. The Guillain-Barré syndrome, peripheral nerve disorders, and behavioral abnormalities may occur at any stage of the disease. Neuropsychological alterations noted during the prodrome of viral hepatitis usually clear without sequelae but abnormalities which follow the onset of jaundice may persist during the convalescent phase for prolonged periods. Neither occurrence, type, nor severity of neuropsychological dysfunction appear to be related to specific hepatitis viruses since both type B and non-B infections have been implicated. Furthermore, neuropsychological dysfunction does not appear to be related to the severity of the hepatitis as assessed by clinical or histological features. Although direct viral invasion of nervous tissue and immune complex-mediated damage have been postulated, the mechanism(s) of neuropsychological abnormalities remains to be determined