PurposeThis cohort study addresses the need for comprehensive and longitudinal research on police officers’ mental health, focusing on the relationship between occupational factors, individual characteristics and mental health status or suicidality. The Mental COP (Mental health Cohort Of Police officers in Korea) research provides important insights by tracking new police officers over time, contributing to evidence-based interventions and policies to improve their overall mental health and working conditions.ParticipantsMental Cop is a prospective open cohort study designed for new police officers for police recruitment, expected to graduate after 8 months of education at the Central Police Academy. To date, 6752 individuals have completed the baseline survey and are enrolled in the cohort.Finding to dateThe study data in Mental COP covered a wide range of issues for first responders, including personal factors, various mental health problems, occupational factors and measured biomarkers of allostatic load, including Heart Rate Variability. The main findings indicate a lower prevalence of mental health problems among those selected as new police officers compared with the general population with notable gender differences. Therefore, closer monitoring of women is required. Furthermore, the study revealed cohort-based differences in mental health, highlighting increased risk related to occupational factors (field training) and the management of vulnerable groups.Future plansAnother wave of Mental COP is scheduled for December 2023, with plans for future cohort expansion. Additionally, it will establish a more comprehensive and systematic scientific framework for future investigations by integrating broader medical examinations and National Health Insurance Service Data.