Forty-seven newborn infants with 1 min Apgar score < 7 were studied. On the third postnatal day the following measurements were made: yellow skin colour, serum bilirubin concentration, reserve albumin concentration and plasma pH. Given the bilirubin concentration and the regression curve between the yellow skin colour and the bilirubin concentration, delta-TcB was calculated as the difference between measured yellow skin colour and the expected yellow skin colour. There was a negative correlation between delta-TcB and Apgar score (P = 0.003), pH (P = 0.026) and reserve albumin concentration (P = 0.045). Fourteen of the included newborns had central nervous system symptoms in the days just following birth. A tendency towards higher delta-TcB was noted in this group (P = 0.08). The results suggest that further study of delta-TcB determination as a tool in the assessment of the icteric newborn infant is justified.