Introduction: According to recommendations, adolescents should be physically active for more than an hour a day, spend up to two hours in front of TV screens and sleep at least for eight hours. It is a well-known fact that nowadays recommendations are ignored, which can have consequences on their education, lifestyle and ultimately, their health. The aim of this research is to determine the level of physical activity, the amount of time spent in front of screens and the duration of sleep in two groups of adolescents at the beginning and at the end of high school education. Based on these three behaviors, adherence to current guidelines for 24-hour movement was evaluated and differences between genders and age groups was examined. Methods: Data were collected from 106 high school students at vocational schools using a self-assessment questionnaire (SHAPES) of their 24-hour behaviours. The average age of students in the first grade is 15.51  1.5 years and 18.65  2 years in the fourth grade. The data refer to physical activity during the school week and weekends, time spent in front of screens and sleep time. Using a two-way analysis of variance, we determined the statistical significance of differences between genders and age groups in physical activity, screen time and sleep time. Fisher's exact test was used to determine the association of gender and age with the prevalence of risky behaviors. Results: The research found that first graders of high school are statistically significantly more physically active than fourth graders (p=0.002). Girls are more active by 61 minutes, while boys are more active by 63 minutes per day. During the week, boys spend statistically significantly more time in front of screens (p=0.028), where for the first grade it is 102 minutes more, and for the fourth grade 25 minutes, while there is no statistically significant difference on the weekend. The interaction between gender and sleep grade is statistically significant (p = 0.040), suggesting that the differences between first and fourth grades depend on gender. While girls sleep longer, boys sleep longer. Girls in the first grade sleep for 419 minutes, and in the fourth grade, the time is extended by 62 minutes. Boys in the first grade sleep 429 minutes, and in the fourth grade, this is reduced by 20 minutes. 3.8% of adolescents adhere to the guidelines for 24-hour movement, the most adhere to the guidelines for physical activity, and the least for time in front of screens. Conclusion: The findings of this research could encourage greater supervision of high school students themselves, education about physical activity and its benefits - especially at the end of high school education, reducing time in front of screens, and improving all negative knowledge about bad lifestyle habits.