A discussion of screening tests for phenylketonuria recommends and provides some data on two tests, lists five disadvantages of urine tests, and discusses three new tests. Also considered are the role of the central laboratory facility and seven suggestions for screening different types of infants at different times. Treatment or followup programs are mentioned with the focus on confirmatory tests and eight references to articles on procedures. Services included as beneficial to a comprehensive multidisciplinary program for longterm followup and care are pediatric, nutritional, nursing, social, psychological, and biochemical laboratory and consultation services. Other considerations discussed are the family of the PKU child, the clinical management of the patients, and the frequent monitoring of blood levels. (LE)