Up to the end of 1978 the Willink Biochemical Genetics Unit had screened 506821 babies for metabolic abnormalities over 10 years--98-99% of the children born in the region. Sixty-nine cases of phenylketonuria (PKU), 42 cases of histidinaemia, and six cases of homocystinuria were detected. As well as treating affected children, the staff of the unit have concentrated on providing full support for their families and maintaining good communications with parents, general practitioners, health visitors, and midwives. A clinic liaison sister has provided valuable support for health visitors and an important link between the unit and community services. A study of the costs of screening and treating cases of PKU for the year 1978 showed that this was cheaper, by pound 569000, than the costs of looking after patients with untreated PKU.