Comparing the results of 1981 and 2012 population censuses in Sri Lanka, thecurrent study examined the impact of the war on the population dynamics in theNorthern and Eastern provinces with a focus on changes in the sex ratio. The sexratio in the population varied by district and also by ethnic group within eachdistrict. On the whole Tamils have a tendency for a female surplus in thepopulation while there is a tendency for male surplus in Sinhala communities and,to a varied extent in Muslim communities in districts with a notable presence ofthese two ethnic groups such as Vavuniya, Mannar and Ampara. This variation insex ratio profiles in different ethnic communities can be attributed to differentlevels of mortality and different rates of out-migration among men and women in the Tamil community during the war and selective in-migration of Sinhala andMuslim men when their respective communities are reestablished in the aftermathof the war particularly in the border areas. The study also examined the impact ofthe unbalanced sex ratio on development challenges, postwar recovery and perceptions of vulnerability in different communities.