Submission to the Medical Research Council by Dr Mortimer and Dr Vandervelde for a grant to Identify and characterise acute hepatitis occurring in the United Kingdom due to non-A non-B viruses. Report summarises current state of scientific research in relation to prevalence of Non A Non B hepatitis, derived from various studies carried out internationally between 1978 and 1980 about the incidence of hepatitis A, B, and Non A Non B.