Introduction: Participating in regular physical activity has positive effects on the health and behavior of adolescents. Physical activity is multifaceted and has both interrelated psychological, biological and environmental effects. Therefore, this study was conducted to determine the level of physical activity of female students and its relationship with their socioeconomic status.

Methods: 630 junior high school students in Mazandaran were selected based on randomized multistage cluster sampling in the year 2017. The tools used for collecting data were pedometers, and demographic and Ghodratnama socioeconomic status questionnaires. Data analysis was done using SPSS₂₃ software with descriptive and inferential statistics (the Kolmogorov-Smirnov test, the one-way analysis of variance [ANOVA], and the Pearson correlation coefficient) at a significance level of P ≤ 0.05.

Results: The results showed that the level of physical activity of students decreased as grade level increased. An ANOVA showed a significant difference between the level of physical activity of students in 7-9 grades, but Tukey’s post hoc test showed a significant difference between the level of physical activity of 7th grade students with 8th and 9th, while the difference between the students of grades 8 and 9 was not significant statistically. Out of all students, 30.72% of students were active and 69.28% inactive. The Pearson correlation coefficient showed that there was no significant relationship between socioeconomic status and level of physical activity.

Conclusion: A vast majority of adolescent girls do not do the amount of physical activity recommended for good health, which is a worrying issue. It is suggested that relevant authorities mobilize basic strategies for changing the lifestyles of adolescent girls, including the development of a comprehensive program of physical activity by specialists.