Background: Adolescence is a developmental stage that marked by role uncertainty, a lot of stress, and emotional instability, all of which lead them to harmful behavior and poor mental health. Adolescent mental health problems are a substantial burden on society and a serious public health concern, it has not been well assessed in low and middle-income countries. This study aimed to determine the prevalence and socio-demographic correlates of of mental health problems among in-school adolescents in Harari region, Eastern Ethiopia. Methods: A cross-sectional study was conducted among 3227 in-school adolescents studying in private and public schools in Harari region, eastern Ethiopia. Multistage sampling was used to select primary and secondary school students who participated in the study. Guided self-administered strength and di culty questionnaire measured mental health problems. Data were double entered, validated, and cleaned using EpiData 3.1 and analyzed using STATA 17. Ordinal logistic regression analysis was performed to estimate the adjusted odds ratio between socio-demographic data and mental health problems.Statistical signi cance was set at p-value < 0.05.Results: The magnitudes of mental health problems among in-school adolescents by subscale was 24.17% (95% CI: 22.72; 25.67) for internalizing and 11.93% (95% CI: 10.85; 13.09) for externalizing problems. High level of internalizing problem score was more likely among rural residents (AOR= 1.63, 95% CI: 1.23; 2.15), married adolescents (AOR=1.41, 95% CI: 1.10; 1.84), attending public schools (AOR=1.44, 95% CI: 1.18; 1.78), and adolescents whose father's occupation was farmer (AOR=1.37, 95% CI: 1.01; 1.86). Likewise, the likelihood of high-level of externalizing problem score was high among rural (AOR=2.43, 95% CI: 1.72; 3.46); married adolescents (AOR=1.43, 95% CI: 1.02; 2.02); adolescents who live with eight and above family members (AOR=1.29, 95% CI: 1.01; 1.65); and adolescents whose fathers' are not educated (AOR=1.59, 95% CI: 1.08; 1.35).
Conclusion:This study revealed that a signi cant proportion of in-school adolescents experienced either internalizing or externalizing mental problems. The ndings highlight the urgent need for better detection, intervention, and prevention strategies for in-school adolescents, particularly focusing on boys, rural residents, public school students, and those whose fathers are farmers and uneducated to reduce mental health problems.