This study examined the effects of truancy on academic performance of Secondary School chemistry students in Ikere Local Government Area of Ekiti State. It specifically find out what constitute truant behaviours among secondary school chemistry students in Ikere Local Government Area of Ekiti state; it determined the causes of truant behaviour among secondary school chemistry students in Ikere Local Government Area of Ekiti state and Identified the negative effects of truancy on academic performance of chemistry students in Ikere Local Government Area of Ekiti state. Three research questions were raised to guide the study. The descriptive survey method was adopted for the study and the population consisted of all chemistry students in all public senior secondary schools in Ikere Local Government Area of Ekiti state. Simple random sampling method was used to select a total of two hundred (200) students from five secondary schools in the local government. A self-developed questionnaire was used for data collection. The face and content validity of the instrument was done by an expert and a reliability of the instrument was obtained through split half method which gave reliability coefficient of 0.90. Data collected were analyzed using descriptive statistics (frequency, percentage and mean) to provide answers to the research questions. The result showed that there was adverse effects of truancy behaviour on the academic performance of chemistry students in Ikere Local government Area of Ekiti State. Based on the findings of this study, it was concluded that there is adverse effects of truancy behaviour on the academic performance of chemistry students in Ikere Local government Area Ekiti State. Based on the findings, it was recommended that: Counseling services should be organized and handle carefully by experts to enable orientate the students on the need to shun the act of truant behaviuor. The school authority and all stakeholders should pay more attention on student’s truancy and possibly place serious sanction on any students cut in the act in order to stop all act of truancy among the secondary school in Ekiti State in general.