This monograph titled _Sex Ratio at Birth in Viet Nam: New Evidence on Patterns, Trends and Differentials_ uses the 15% sample data of the 2009 census and provides the most comprehensive and updated information to readers on the current trends of the SRB in Viet Nam. It also provides relevant information on the geographic and socio-economic characteristics of the SRB phenomenon in the country, and attempts to provide scenarios of possible future evolution of this indicator and the impact it may have on society.