The study examined the effects of Advance Organizer teaching strategy on Students’ Gender in Secondary School Chemistry in Ekiti State, Nigeria. The research designed adopted for the study was non-randomized, non-equivalent pre-test and post-test control group design. The population consisted of all senior secondary class two (SSII) students taking Chemistry in Ikere – Ekiti while sample consisted of 97 senior secondary school two students were drawn from intact classes using purposive sampling technique. The instrument used for the study was Chemistry Achievement Test. The face and content validity as well as reliability of the research instrument were carried out and reliability coefficient of 0.86 was obtained. The results of the data collected from both pre-test and post-test were collated and analysed using statistical tools involving mean and standard deviation, graph t-test and Analysis of Variance (ANOVA) at 0.05 level of significance using). The findings of the study showed that students operate at moderate level performance in Chemistry before their exposure to expository advance organizer. However, the use of expository advance organizer improves the performance of students in Chemistry more than conventional method of instruction. Also, it was found that score level and gender classification of students has no influence on their academic achievement when exposed to expository advance organizer. Based on the findings, appropriate recommendations were made.