The purpose of Census is to collect evidence about migrations, demographic, economic, educational, housing characteristics of whole population. Census data in most reliable source for comparisons in time and between countries. At the same time it enables most fine graded geographical units' description. It forms a permanent base for policy and legislative decisions. A micro sample is a valuable source for educational and scientific purposes. It enables flexible analysis of multiple variables simultaneously and thus more deep study of determinants of particular phenomena. First modern census, that encompasses Slovene territory, was conducted in Austro-Hungarian Empire in 1857, followed by 1869, 1880, 1900 and 1910 Census. Two interwar Censuses in 1921 and 1931 was followed by reduced in content Census of 1948 that was meant to gauge situation of population after World War II. We have 1961, 1971, 1981, 1991, 2002 census and last one in year 2011. Censuses were slightly changed from one period to another by selection of variables and exact methodological approach, that needs to be taken into account in comparisons.