The informational age and the globalized economy of the world require constant and unpredictable changes, so the main capital of today is precisely knowledge, so it is not surprising that the 21st century has been declared the century of knowledge. As informational literacy is a key competence for lifelong learning, which is a priority for the development of the knowledge society towards which the Republic of Croatia is also directed, an effort was made to examine how well the graduates are prepared for the requirements set by the informational society of the 21st century. This paper deals with research of informational literacy of high school graduates and graduates of four-year vocational schools who completed their high school education in the 2020 /2021 school year. The research was conducted on a sample of 222 respondents in four secondary schools in Zagreb in order to determine which information literacy skills the graduates have mastered, or which skills they lack, in order to obtain real data on the level of their information literacy and whether the diversity of educational programs affects level of information literacy. The paper presents an analysis of the results of the conducted research, discusses certain factors of informational literacy in the educational system, and offers suggestions for improving the information literacy of high school students, as well as suggestions for future research. Based on the results of this research, it will be possible to use the obtained results to improve the teaching of information literacy in high school.