Suicide rates in young Irish males have risen markedly in the past 10 years, and suicide is now the leading cause of death in young men in the 15-24-year-old age range. This is the first large-scale study in Ireland that set out to identify young people at risk of psychiatric disorders, including depressive disorders, and suicidal ideation. Seven hundred and twenty three school-going adolescents aged 12-15 years were screened using the Children's Depression Inventory and the Strengths and Difficulties Questionnaire. 19.4% were identified as being "at risk" of having a mental health disorder. Of this "at risk" group, 12.1% expressed possible suicidal intent and 45.7% expressed suicidal ideation. Of the 583 adolescents identified as being "not at risk", 13% expressed suicidal ideation while none expressed suicidal intent. Being "at risk" was not related to gender or to socio-economic status. Those living with two parents were significantly more likely to be in the "not at risk" group. Girls attending co-educational schools were twice as likely to be in "at risk" group compared with those attending all girls schools, while school type was not a risk factor for boys. This study shows that, as in other western countries, there are large numbers of young Irish people at risk of mental health disorders and suicidal ideation in the community, and raises the question of the importance of mental health promotion in our education system.