This study examines the sex of the first-born children on education and health outcome of later born children. We do not find a significant effect of the sex of the first-born children on health utilization of later born children. However, we find some small effects of education. Once controlled for the number of sibling, having a firstborn brother reduces the probability of school enrolment and the probability of having good academic performance. Although the education outcomes of girls are higher than boys, this evidence still indicates gender bias in education investment of parents in their children in Vietnam.