Youth suicide is like the tip of an iceberg; while many adolescents have died from suicide, many more adolescents have been harmed by suicide attempts and self-injury. Suicide influences not only the victims, but also their family members, friends, teachers, and neighbors. Witnesses can suffer from posttraumatic stress disorder. Suicide is the second leading cause of death among adolescents worldwide and the first cause of death among Korean adolescents. The number of suicides in Korea, especially among high school students and female students, is rapidly increasing when compared with Western countries. Suicide accounted for 28.2% of deaths among Korean adolescents in 2010. There were 4.44% and 18.97% of adolescents who had attempted suicide and had experienced suicidal ideation in their lifetime, which shows that many adolescents have a potential risk for suicide. Previous studies in Western countries have revealed that risk factors for adolescent suicide consist of three categories: sociodemographic factors (male and low socioeconomic and educational status), mental health factors (depression and drug abuse), and individual negative life events and family diversity (family history of suicidal behavior, parental death, and child abuse). In conclusion, suicide is common and rapidly increasing in Korean adolescents. However, the risk factors of suicide and suicide behaviors in Korean adolescents are yet to be determined. A well-designed nationwide survey is needed to investigate the prevalence and risk factors of suicide behaviors and mental disorders among Korean adolescents.