The psychosocial aspects of phenylketonuria (PKU) were investigated retrospectively in the families of 25 children and adolescents with classical PKU. With the help of a semistructurated questionnaire the parents were asked in interviews what impact the birth, the diagnosis of PKU in their child and the treatment itself had on them. 19 of the children had been detected by newborn screening and given early treatment. With one exception they all showed adequate intellectual development. Six other children were diagnosed late and only three of them had been given dietary treatment with some degree of success. Many of the parents reacted with shock and disbelief after being informed that their child was abnormal. In many ways the parents expressed retrospectively the wish that they had been better informed about their childs disease and had more intensive support from the medical professionals. They believed that with these prerequisites they would have been more competent in the case of their children. The data demonstrate the necessity of psychological care for the entire family of the chronically sick child.