Research was carried out on the sample of 107 students of Oton Iveković, primary school, in Zagreb, with the aim of estimating physical activity of primary education students aged 8 to 10, i.e. those of 2nd to 4th grade of primary school. Out of the total number of students 54 boys and 53 girls took part in the research. The main aim of the research was to check the amount of physical activity based on gender and age, as well as, to determine possible differences by means of t-tests. The research was conducted in February of 2020 by using a questionnaire for estimating the amount of physical activity which contained five questions. The students completed the questionnaire independently, previously explained and supervised by the examiner. Namely, the third grade pupils are slightly more active than the second grade pupils, but not in all the variables, therefore the difference was not statistically relevant. The research also proved that girls are more active than boys in most of the variables, although significant difference was not confirmed either. Boys demonstrated greater activity than girls only in the amount of training in sports clubs, however the difference was not statistically significant. On the basis of the obtained results it can be concluded that there are not significant differences among students of different age and gender, therefore hypotheses 2 and 3 referring to the existence of significant differences based on age and gender are rejected.