OBJECTIVE To understand the prevalence of myopia in primary and middle school students in 6 provinces and the possible influencing factors. METHODS Primary and middle school students were selected through multistage cluster sampling in 60 primary and middle schools in 6 provinces in China. The questionnaire survey and eyesight test were conducted among all the students selected according to the national student's physique and health survey protocol. Pearson chi-square test and binary multivariate logistic regression analysis were done to identify the influencing factors for myopia in students. RESULTS The prevalence of myopia among primary and middle school students surveyed was 55.7%, the gender specific difference was statistically significant (59.7% for girls, 51.9% for boys) (P<0.01). The prevalence of myopia increased with age obviously. The prevalence was 35.8% in age group 6-8 years, 58.9% in age group 10-12 years, 73.4% in age group 13-15 years and 81.2% in age group 16-18 years, the differences were statistically significant (P<0.001). Single factor and multivariate analysis showed that parents' myopia, distance between computer screen and eyes, distance less than 30 cm between eyes and book while reading, distance less than 10 cm between chest and the table edge while studying, distance less than 3 cm between fingers and pen tip, sleep time, average outdoor activity time during last week, school sport activities in the afternoon, the size of television set at home, time spent on watching TV and playing computer were the influencing factors for myopia. CONCLUSIONS The prevalence of myopia is till high in primary and middle school students. Myopia is associated with both genetic factors and individual eye health related behaviors.