Abstract Background Uncorrected refractive errors, one of the most common health problems of the pediatric age group. It is known that outdoor activities are effective in the prevention of refractive errors in childhood. The aim of the study was to evaluate the frequency of refractive errors in primary school children and their relationship with outdoor activity. Methods This croos-sectional study conducted with 4th grade primary school students in Eskisehir in 2023. Schools in the city center were divided into clusters according to their socio-economic status. Then, 1009 students from seven schools selected according to their randomization weights were included in the study. A questionnaire including sociodemographic characteristics, The Physical Activity Questionnaire for Older Children (PAQ-C) and questions about outdoor activities was administered to the students. They were examined for visual impairments. Outdoor activities were taken on weekdays and weekends and the daily average value was calculated. Results The mean age of the students was 9.8±0.5 years and 52.3% of them were female. Of 16.4% students had refractive errors, 5.85% had strabismus and 1.20% had depth perception deficits. Students with refractive error had lower scores on the PAQ-C scale and lower mean daily outdoor activity duration (p < 0.001 for each). In multivariate analysis, the risk of refractive error was found to be higher 4.61 times in those with good income (OR; 95%CI; 1.975; 10.75), 4.55 times in students who have visual impairment other than refractive error (OR; 95%CI; 3.01; 6.83), and 2.63 times (OR; 95%CI; 1.75; 3.95) in those who did outdoor activities for two hours or less a day. Conclusions Physical activity and outdoor activity duration were shorter in students with refractive errors. The risk of refractive error was found to be higher in those with good income, who have visual impairment other than refractive error, and those who did outdoor activities for two hours or less a day. Key messages • It is important to include regular screening programs on visual impairments and physical activity within school health studies. • In order to prevent the development or progression of refractive errors, children should be encouraged to engage in outdoor activities during the day.