Retrospective analysis of the case records of 465 babies with a birthweight between 1·0 kg and 2·0 kg, born during 1960-67, showed that 17·9% were described as `blue' on arrival in the special care nursery, and that their mortality from hyaline membrane disease was 28·9% as compared with 6·8% in those described as `pink'. The overall mortality from hyaline membrane disease was 10·8%. After the adoption of a policy of earlier use of oxygen under intermittent positive pressure, and more careful supervision of the environmental conditions during transfer to the nursery, the proportion of babies described as `blue' on arrival fell to 5·4% (a statistically significant improvement), and the overall mortality from hyaline membrane disease fell to 6·5% (not a significant improvement on the numbers available so far).