The prohibition of prenatal sex selection regulation was issued in 2003 in order to prevent imbalance sex ratio at birth in Vietnam. This article is extracted from a research conducted in 2011 to 2013 in two provinces (one in the North with highest sex ration at birth imbalance and one in the South with the lowest level). The objective of this article is to analyses regulation process on prohibition of prenatal sex selection. The desk review, secondary data analysis and qualitative research (in-depth interview and group discussion) were applied with policy makers, implementers and mothers having a child under 2 year olds. The result showed that, the processes of prenatal sex selection have followed the steps of policy process. However, the administration process (Decree 104 and 114) has begun late. The activities in implementation process also a difference between two research's provinces
especially nearly no activity has been done in the Southern provinces due to sex ration at birth imbalance was not a priority. Limited recourse (lack of budget and inspector) and son preference were affected to the implementation process.