Generally, the mean age at menarche appears to be falling, and many girls attained menarche unprepared. This study assessed the preparedness of female secondary school students in Ile-Ife in Osun State towards menarche. This cross–sectional descriptive study was carried out among 797 female students selected through multistage sampling method. Semi-structured, self-administered pretested questionnaires were used as research instrument. Data was analyzed using the Statistical Package for Social Sciences software version 23.0. Mean age of respondents was 18.4 ± 2.7 years. A total of 89.6% (714) of all the respondents were informed about menarche before its onset; 73.2% (527) of them were informed by their mothers. About 69.3% of the respondents had good knowledge score of menarche while only 65.9% of them were scored as prepared for menarche. Predictors of being prepared for menarche include higher age at menarche, and being pre- informed about menarche. There is still need to fill the existing knowledge gap among the respondents through adequate school health education program.