Introduction. Nutrition is one of the key elements of shaping health-promoting behaviours. One of the most important health-promoting behaviours is physical activity, which brings numerous health benefi ts. Family plays a crucial role in forming health behaviours: the more health-promoting behaviours young people learn at home, the higher the chance is of them continuing these behaviours in their adult lives. Aim. Researching the presence of health-promoting behaviours among middle and high school students. Materials and method. 551 students participated in the research. The research was conducted with the use of an online questionnaire in Google Forms. It was conducted in February and March 2021. A questionnaire developed by the author was employed, as well as the International Physical Activity Questionnaire (IPAQ – short version). Results. Nearly half of the research participants ate sweets a few times a week. Research has shown signifi cant differences in health behaviours between genders. Signifi cantly more boys (7.9%) than girls (3.1%) ate fast food a few times a week. Boys ate fi sh signifi cantly more often. Signifi cantly more boys than girls consumed fi zzy drinks a few times a week or every day. Conclusions. Over half (51%) of the students were moderately physically active. 34.1% were highly physically active, and the physical activity of 14.9% is low. Girls showed more health-promoting behaviours than boys. Girls went on a diet signifi cantly more often than boys. Boys consumed signifi cantly less fruit than girls. The COVID-19 pandemic led to decrease in physical activity among students.