Background: Myopia is a refractive error of the eye that are commonly in school children, and the prevalence of myopia is increasing. Myopia affects quality of life and learning abilities of students. Objective: To determine the prevalence of myopic high school students and conditions of school hygiene in some high schools in Bac Giang city, Bac Giang province. Subjects and Methods: A cross-sectional descriptive study was conducted in Ngo Sy Lien high school and Bac Giang high school for the gifted in 2010. Results: Of total 768 high school students, the prevalence of myopia was 53.3 percent, the highest prevalence of myopia was 64.4 percent in 12th grade students and lowest prevalence in 10th grade students accounted for 45.9 percent. The majority students had mild myopia (60.7 percent) and the prevalence of myopia in female students (56.8 percent) is higher than male students (47.9 percent). The average of class area square per students was 1.00 + or - 0.04 in Ngo Sy Lien high school and height of class in two schools (3.4m and 3.35 m) were less than standard criteria. The subtraction of table and chair was higher than standard criteria. Condusions: The prevalence of myopia in high school students is high, the subtraction of table and chair and height of class are inadequate standard criteria.