Phototherapy—how should it be used; who should receive it; is it safe? In June of 1969, the Stritch School of Medicine and the National Foundation sponsored a symposium entitled "Bilirubin Metabolism in the Newborn" and published the proceedings in the Original Article Series. This symposium brought together many of the leaders in the field of neonatal bilirubin metabolism to discuss the state of phototherapy in treatment of neonatal hyperbilirubinemia. This volume can generally be divided into three parts. The first deals with the development of the present understanding of perinatal bilirubin metabolism; the second, some experimental effects of light therapy; and the third, clinical experience with phototherapy. Much of the clinical and experimental data presented is new and comprises a large part of today's knowledge concerning phototherapy. Data presented here, together with previous studies firmly establish that phototherapy can lower the serum level of indirect bilirubin. As could be expected