Objective: Despite growing international interest in the area of violence and suicidal ideation among school-going adolescents, epidemiological data are scant in Portugal. The objective of this study was to measure the prevalence of suicidal ideation among Portuguese adolescents from 7th to 12th grade and to estimate the association of violence exposure with suicidal ideation. Method: A cross-sectional survey was conducted among 2 602 adolescents enrolled in public schools in Porto, Portugal. Sampling was performed in four school groups consisting of seven schools, during the 2014/2015 academic year. Results: The results revealed that 11.4% of Portuguese school-going adolescents reported suicidal thoughts during the past 12 months. Moreover, adolescents who had been involved in physical fighting were two times more likely to have suicidal thoughts. These odds substantially increased when bullying and cyberbullying victimisation were included. Conclusion: Effective interventions with multidisciplinary efforts involving parents, school teachers, principals, and mental health professionals, should be integrated into school-based programmes to improve adolescents' mental health and strengthen them against suicidal ideation.