The main goal of this graduation thesis is to present demographic changes in the City of Knin which were the result of migration movements. Data sources included population censuses for 1991, 2001, 2011 years as well as all after WW2 population censuses and vital statistics about fertility and mortality of the Croatian bureau of statistics. City of Knin was directly affected with Croatian War of Independence which resulted the huge demographic changes. These changes are visible in lower population number in all settlements (except Kninsko polje), populations concentration in Knin, very small number of domestic population, changed national structure and immigration from Bosna and Hercegovina, and perturbed age and sex ratio. Because of all this we can talk about extreme populations cuss, relatively with settlements where living just old age population and where is missing some age category. The process of demographic aging is very pronounced as evidenced by the fact that almost a third of the population in the settlements belong to the type of very advanced old age and extremely advanced old age.