INTRODUCTION I have not been able to find a comprehensive analysis. of the experience of any one pediatric service with jaundice in children. Although there are several classifications of jaundice, notably those of Rich,1Barron2and Martin,3they are based either on postmortem examinations and experimental work or on a study of a group of adults. Since many conditions which commonly give rise to jaundice in adults are extremely rare in infants and in children, while conditions which are frequent and important in children seldom if ever occur in adults, it seems desirable to have a classification based on pediatric experience. I have attempted to pick the best classification from that point of view. In addition, I have summarized the existing experimental evidence regarding the various types of jaundice, the mechanism of their Production, and the tests which are important in differentiation and I have included an