Deviant behaviours in schools are behaviours that do not conform to the school norms, culture, rules and regulations. This study is about the teachers’ perceptions of the prevalence of deviant behaviours among the senior secondary two students in mainland zone two. The target population was all the senior secondary teachers in Mainland zone two, with 128 males and 152 female teachers. Data was collected using a self-structured questionnaire divided into two sections. Section A comprises the demographic data, while section B has 16 items. The items had subheadings, namely deviancies due to attack on school authority, deviancies relating to attacks on persons or properties, deviancies due to student’s gang attacks and deviancies relating to the poor reading study. The study was guided by one research question and two hypotheses. Mean and standard deviations were used to analyse the data while t-testing the null hypothesis at a 0.05 level of significance. Results showed no statistically significant difference between the perceptions of male and female teachers on the prevalence of deviant behaviours in schools. Still, there was a statistically significant difference in perception based on teachers’ age group. Recommendations were made, including provisions for counsellors, and regular seminars/workshops on deviant behaviours to students, school authorities, teachers and parents.