. Effect of albumin administration on phototherapy for neonatal jaundice. Two clinical trials were designed to test the effect of albumin administration before phototherapy for non-haemolytic neonatal jaundice. The first with 18 hours of phototherapy showed that the albumin-treated group (23 infants) had higher and more prolonged jaundice than the group (27 infants) given phototherapy alone.In the second study on 29 infants there were two groups as before, but the duration of phototherapy was increased to at least 48 hours and a third untreated group was included. These results showed significant differences between all three groups, the cases receiving phototherapy alone having the shortest and those receiving no specific therapy, the longest duration of jaundice.Those patients given albumin intravenously had significantly greater albuminbinding capacity at the end of treatment.It has been shown that administration of intravenous albumin raises the intravascular fraction of bilirubin (Odell, 1959a and b) (Wood, Comley, and Sherwell, 1970). Since phototherapy was introduced (Cremer, Perryman, and Richards, 1958), it has been shown to lower plasma bilirubin levels in neonatal jaundice (Broughton et al., 1965;Lucey, Ferreiro, and Hewitt, 1968).The present study was planned to observe the effect of albumin administered intravenously before phototherapy. It was also hoped to discover whether the light acted on the extravascular or intravascular component of bilirubin mass; thus, if light breaks down bilirubin in the extravascular space, then administration of albumin should decrease its effect by withdrawing bilirubin into the intravascular component. Conversely, administration of albumin should enhance the effect of phototherapy if it destroys the bilirubin circulating in the blood stream.