Letter from Dr J Craske (Withington Hospital) to Dr C.A. Ludlam (Royal Infirmary of Edinburgh) regarding the meeting of the Hepatitis Working Party and discussions between the Royal Free Hospital, Sheffield and Oxford about the best method of conducting investigations of the incidence and clinical features of chronic hepatitis in haemophiliacs. Dr Craske strongly urges avoiding the use of commercial products as it is likely that patients will be exposed to a fresh type of non-A, non-B hepatitis.