The indiscipline challenge in schools is ranked as a major problem among students of primary and secondary schools in Ethiopia. Disruptive behavior is a concern to schools and parents and to fellow pupils, whose education may be adversely affected. The aim of this investigation was to identify the level of students' discipline problems and the degree of disruption to teaching and learning in senior secondary schools in the Eastern part of Ethiopia (SSEE). This study surveyed four hundred teachers and one thousand five hundred sixty students at SSEE. Results of the study confirmed that students and teachers were experiencing high levels of school indiscipline with the most frequent being cheating, disrespecting teachers and principals, late coming, skipping classes, hyperactivity, and lack of concentration, deliberate defiance of school policies, and using mobile phones in classes. In addition, the degree of the effect that indiscipline in teaching-learning was extremely high in the study area. The study highlights the necessity for further assessment of the causes and management of indiscipline in Ethiopian secondary education classrooms.