Letter from Nicol S. Galbraith, Public Health Laboratory Service Board (PHLSB), to Dr. Ian Field, Department of Health & Social Security (DHSS). Details a case of a haemophiliac in Cardiff with suspected AIDS who received USA factor VIII concentrate. Concludes that all blood products made from blood donated in the USA after 1978 should be withdrawn from use until the risk of AIDS transmission by these products has been clarified. A paper called Action on AIDS is appended which sets out the reasons for the proposal.