The COVID-19 pandemic represents a major challenge for education systems. The introduction of sex education in Croatian schools has not yet been achieved; hence, the demanding role of sex education is left to parents and headroom teachers (the latter without proper curriculum and/or training). Adolescence is the period when the foundations of sexual relationships are formed for adulthood, which are later strengthened during the years of sexual activity. The risk of poor sexual health is reduced by proper information and responsible sexual behaviour, i.e. sexual education. This thesis is tackling the issue of the availability of sex education in secondary schools before and during the COVID-19 pandemic, when social contacts and student-teacher interactions were minimized. There was a statistically significantly lower acceptance of claims regarding sex education in high school students during a pandemic compared to the acceptance of claims before a pandemic (z = -7,569 p <0.001), with a substantial difference (r = 0.51). The median attitudes fell froman average of 3.50 to an average of 2.06. This test refers to the overall sample in this study, where a decline in pandemic period (compared to pre-pandemic time) was reported in 87 high school students from 109 in total (i.e., 80% of them). Pre-pandemic sex education was available to 63% of high school students surveyed while the remaining 37% did not have it in any form. The availability of sex education for high school students at the time of the pandemic dropped from63% to 23%. Further research is needed to determine the consequences that the COVID-19 disease pandemic will have on the sexual and reproductive health of young people, which are inevitable due to the non-continuous education of young people.