The experience gained in a pilot programme for multiple screening for amino acid disorders is reported. Over 222,000 newborn infants were screened by ion-exchange chromatography using dried blood spots. The acceptability, reliability and validity of the method are reported, and an outline is given, of the field evaluation of the method over 4 years, together with a short cost analysis. Incidences of the screened diseases and their differences from other reports are also discussed.