Background: Correct and culturally relevant sexual and reproductive health knowledge among children and adolescents is a key component to a healthy life. In Mexico, a country plagued with a teen pregnancy epidemic, sexuality education in the public-school system begins in 4th grade. Our study aims were to characterize the sexual and reproductive health knowledge of middle school students from Oaxaca, and its association with belonging to an indigenous group, gender, sources of sexual and reproductive health information, and parents’ level of schooling. Methods: Cross-sectional study. Students responded to a multiple-choice paper and pencil selfadministered survey on sexual and reproductive health knowledge. Our sample included 245 middleschool students (51.4% were female) enrolled in rural school’s 7th, 8th, and 9th grade. Survey contents were based on the Ministry of Education textbooks.