BackgroundIn 2017 WHO reported that due to a lack of menstrual hygiene management (MHM) facilities, high costs, and ignorance, 2.3 billion girls and women worldwide do not manage their menstruation properly. This leads to the use of other options, such as old clothes or other unhygienic materials, which may make them a risk group for infections and other health consequences. Despite the significant role of appropriate menstrual hygiene practices, it is still a missed opportunity to address the hygienic practice of menstruation among girls in many low-and middle-income countries, including Ethiopia.ObjectivePrimarily, this study was aimed at investigating menstrual hygiene management (MHM) practice and determinant factors among young adolescent school girls in eastern Ethiopia, Gursum District 2021.MethodAn institutional-based cross-sectional survey was conducted among adolescent school girls in Gursum, Eastern Ethiopia, in 2021. 577 girls participated in this study and a multi-stage sampling procedure was employed so as to select a fair and representative sample of female students who experienced menarche. After controlling for confounding variables, binary logistic regression was fitted to identify factors affecting MHM among adolescent girls.ResultThis study revealed that 58.41% of adolescent school girls practice unsafe MHM practices. It was also reported that 193(33.45%) of the girls use reusable sanitary pads. Of those, 182(31.5%) of them keep the pads in hidden places as it is a shame to be seen Seventy-six (13.17%) of the respondents had experienced vaginal infections during menarche. Having knowledge about menstruation prior to experiencing menstruation [AOR 0.28 CI: (0.1476132, 0.5613692)], being over 15 years old [AOR 1.56, CI: (1.020577, 2.387646)], living in rural areas [AOR 1.23 CI: (1.1563013, 1.3562546)], and having infection around their vagina during menarche [AOR 4.6 CI: (2.633405, 8. 273,883)] were significant determinants of MHM practice.ConclusionThe majority of the adolescent girls who participated in this study practice unsafe MHM practices. Results suggest that school health education focusing on improving the hygienic practices of adolescent girls during menstruation should be provided.