Suicide among children and young adults is a leading cause of mortality, highlighting the importance of the development of life-saving interventions. This study is part of the nationwide study Retrospective investigation of health care utilization of individuals who died by suicide in Sweden in 2015, Lund University, Sweden. The aim was to gain a better understanding of verbal suicidal communication and suicidal behaviour in children and young adults who die by suicide, to analyse gender and age differences, and to discuss the findings in relation to the prevailing psychological theories of suicidality. The study sample consisted of medical records from final health care consultations of 114 individuals up to 25 years, who died by suicide in Sweden a single year. Suicidal plans were documented in 13 percent of children and young adults. Females were more likely to have a notation of suicidal communication than males. Twenty-seven percent had made previous suicide attempts. Approximately 90 percent of the study cohort had contact with health care settings within 24 months prior to suicide. Questioning about suicidal plans appears to be an insufficient tool to assess suicidality in children and young adults. Clinical implications regarding alternative assessment methods and preventive measures are discussed.