The doctoral dissertation analysis of changes in the educational structure of the Republic of Croatia compared to other EU member states in the period 2001-2018. The sources of data were censuses, statistical reports, and specially processed data from the Croatian Bureau of Statistics and Eurostat. In the analysis were used demographic statistics method with comparative analysis for the total population and distribution by sex and age. Education is an important factor in an individual's life, and it has a lasting effect on his or her attitudes and norms, and through it acquires knowledge and competences for the further life. Changes in educational structure also affect other sociological and demographic behaviors. People enter the process of education in pre-schools, or kindergartens that prepare them for primary education, during which basic knowledge is mastered, among other things, this includes writing and reading. Historical and economic factors (especially wars) caused a difficult socio-economic situation in the Croatia, which negatively affected on the Croatian population and their education. A lot of Croatian older people had lower educational opportunities, which resulted in a higher proportion of the illiterate population. The development of primary education and the legal regulation on compulsory primary education has reduced the share of illiterates in Croatia in recent decades and changed the primary level of the educational structure. Despite of it, the illiteracy rate was 1.8 % in 2001 among the population aged 10 and more, with a significantly higher proportion of the female population, and the proportion decreased to 0.8 % in 2011. The decrease of one percentage point was mainly due to biological factors, namely the death of the older female population aged 65 and over, whose share in 2011 was 61.32 %. As younger women had greater educational opportunities, so all younger population had a lower proportion of illiterates. It is very likely that due to the age structure of the illiterate population, the proportion of illiterates will decrease to an insignificant level in 2021 when the next census will be conducted.