摘要:Background: Menarche is the first menstrual period of a girl at puberty. The timing of menarche is significant for health in future life. Saudi Arabia has developed immensely over the last three decades as evidenced by the economic and health sectors throughout all parts of the vast Kingdom. The current study measured the menarche age of school adolescents Girls in Saudi Arabia and explored environmental factors that could impact the onset of menarche. Method: This cross-sectional study was conducted on 1486 healthy Saudi school adolescents’ girls between 10 - 19 years old. The data were collected in 2016 using self-administered questionnaires. Health status, dietary intake, physical activities and parent’s education were recorded along with other environmental factors. Data were analyzed using SPSS version 17.1. Results: Out of 1486, 767 girls (51.6%) had experienced menarche with a mean age of 12.46 ± 1.57; 681 girls (45.8%) had experienced menarche at age of 13 - 15; 38 girls (2.6%) had experienced menarche at age of 16. A significant association between menarche and social factors was detected. Besides, the study discovered a significant association between menarche and the lifestyle of the studied groups.