<![CDATA[Background: Menarche is an important event that marks the beginning of puberty in girls. Adequate knowledge during elementary school years is essential to reduce anxiety, misconceptions, and negative attitudes toward menstruation. The lack of systematic reproductive health education may leave female students unprepared to face menarche. Therefore, menstruation education is needed to improve students’ understanding before they experience menarche. Objective: This study aims to determine the effect of menstruation education on knowledge of menarche among female students at SD Negeri (State Elementary School) Jetisharjo, Yogyakarta. Methods: This study employed a pre-experimental design using a one-group pretest–posttest approach. The study population consisted of 57 female students who had not yet experienced menarche, all of whom were included as the sample using a total sampling technique. Data were collected through pretest and posttest questionnaires and analyzed using the Wilcoxon test. Results: Before the educational intervention, most respondents had a good level of knowledge (52.6%), while 42.1% had a moderate level and 5.3% had a poor level. After the intervention, the proportion of respondents with good knowledge increased to 86.0%, the proportion with moderate knowledge decreased to 14.0%, and no respondents remained in the poor knowledge category. The results of the Wilcoxon test showed a p-value of 0.000 (α < 0.05), indicating that menstruation education had a significant effect on improving knowledge of menarche among elementary school girls]]>
