Objective: Reproductive health (RH) is a crucial aspect of general health; it is a reflection of health during adolescence and adulthood. The period of adolescence in females is a period of physical and psychological preparation for safe motherhood. As direct reproducers, adolescent girls' health influences not only their own health but also the health of the future generation. This study aimed to assess knowledge, hygiene practices during menses, and attitudes of female adolescents in Riyadh female secondary schools regarding RH aspects. Methods: A quantitative descriptive cross-sectional design was used for this study conducted on 350 female students selected from governmental secondary schools in Riyadh using multistage random sample type. Two tools were used for data collection in the current study: a self-administered questionnaire and an Attitudinal Assessment scale. Results: The findings showed that more than two-thirds (66.3%) of the participants had inaccurate knowledge, while about one-third (33.7%) of them had correct knowledge regarding RH. With respect to overall hygiene practices during menstruation, about 95.4% had correct menstruation hygiene practice, while only 4.6% had incorrect practices. The majority (88.3%) of students had positive attitudes regarding RH, while only 11.7% had negative attitudes. Mothers are a vital source of information regarding RH. Conclusions: The present study concluded that female adolescents had unsatisfactory knowledge, inadequate hygiene practices, and positive attitudes toward RH. It is recommended to improve adolescents' knowledge regarding RH issues and involve their parents and teachers to provide appropriate education related to RH issues.