Bilirubin was determined by direct spectrophotometry and by the candidate reference method of Doumas et al. (Clin. Chem. (1985) 31; 1789-1798) in a group of more than 230 newborns, and the results were compared. Direct spectrophotometry by Vink et al. (Clin. Chem. (1988) 34; 67-70) gives the following regression equation in comparison with the reference method: y = 0.967x + 6.57 with r = 0.9874...