The aim of the research was to examine the level of physical activity of users of the social network in Croatia, the relation of the sociodemographic characteristics and the level of physical activity compared to the time spent on the following activity. The study involved 333 respondents who are active users of Facebook (FB). The short version of the IPAQ questionnaire and BMI Calculator were used to assess the physical activity of respondents. This research has determined that the BMI index (BMI) ranges from 16.04 to 42.25, average 24.00. The total level of physical activity of the participants, expressed through the Metabolic equivalent task (MET) is high, and according to the MET category the participants are in the high level of involvement category or HEPA active. There is a statistically significant correlation between the overall results obtained with the IPAQ compared to the MET category, BMI, quality of life and self-assessment of health in FB users. Participants spend on average 5 hours per day sitting during a week, and there is statistically significant correlation between the overall results of the IPAQ compared to the MET category and the time spent sitting. In conclusion: that involvement in social networks for participants in this study does not disturb the level of physical activity.