Background: Hygiene throughout the menstrual cycle is a significant public health concern, yet it is not recognized or appropriately addressed in many parts of Jordan. Purpose: The study aims to assess the level of knowledge and practices of menstrual hygiene among adolescent schoolgirls in the Jordanian Badia region. Methods: A descriptive cross-sectional study was conducted from February to March 2022. Data was collected from a convenience sample of 550 girls aged 12 to 18 years from six schools for girls in the Badia region using a questionnaire that assessed knowledge and practices of the menstrual cycle. Descriptive statistics (mean, standard deviation, frequency, percentage) and multivariable logistic regression analysis were used to determine the predictors of the https://jjnr.just.edu.jo/jjnr/ Menstrual Hygiene - 2 - level of knowledge and practices of the menstrual cycle. Results: The mean age of the participants was 15.5 years. About 65% of the adolescent schoolgirls have adequate level of knowledge. Regarding practices, around 58% of the adolescent schoolgirls have a poor level. The highest score was for” Schoolgirls should have a discussion with their mothers about menstruation and what to do during their periods”, while the lowest score was for “If she has to, she will have to change the pads at school”. In multivariable analysis; age >16 [OR = 2.10, 95% C.I (1.91–2.23)], mothers’ highest level of education [OR = 2.32, 95% C.I (2.25–2.39)], and family income [OR = 1.71, 95% C.I (1.58–1.83)] were the predictors of safe knowledge and practices of the menstrual cycle. Besides, age >16 [OR = 2.21, 95% C.I (2.11–2.33)], mothers’ highest level of education [OR = 2.89, 95% C.I (2.69–2.92)], and family income [OR = 2.01, 95% C.I (1.90–2.15)] were the predictors of practices of the menstrual cycle. Conclusion: Overall, the adolescent schoolgirls are reasonably knowledgeable of menstrual hygiene. On the other hand, the girls' overall level of practices was poor. So, menstrual hygiene knowledge and practices need to be improved by educating girls about menstruation and menstrual hygiene before menarche in order to protect them against Reproductive Tract Infections (RTIs). Implications for Nursing: There is a need to teach girls about the importance of personal hygiene to have confidence in themselves. Keywords: Knowledge, Practices, Menstrual hygiene, Adolescents, Schoolgirls.