This report is the first global review of sex differentials in infant and child mortality produced by the United Nations in over a decade. The results of this study highlight the importance of estimating childhood mortality rates seperately by sex. In many areas of the world, advances in survival appear to be accruing relatively equitably to girls and boys. In many of the less developed regions, girls' past disadvantage in mortality at ages 1-4 appears to be easing. However this is not universally the case. In China and India there is evidence that girls are not benefiting as much as boys from the national trends of mortality decline. On the other hand, several countries had findings suggesting a greater than expected degree of male disadvantage in survival during infancy.