Child and adolescent inpatient treatment has faced major changes since the year 2000, including shorter inpatient stays and a greater use of psychotropic drugs. This study explored changes and correlates of suicidal threats and suicide acts among inpatients, by comparing Finnish cross-sectional surveys from 2000 to 2011. A questionnaire that explored the background, diagnosis and treatment characteristics of inpatients was sent to all child and psychiatric wards in Finland. The data collection was carried out on specified days in 2000 and 2011. We received comprehensive data on 504 patients from 64/69 (93%) wards in 2000 and on 412 patients from 75/79 (95%) wards in 2011. The Spectrum of Suicidal Behaviour Scale was used to explore suicidality. The prevalence of suicidality did not change in this nationwide study: suicidal threat rates were 38% in 2000 and 37% in 2011, and suicide attempts in both years were 11%. The prevalence of suicidal acts was higher among girls and teenagers, while low general functioning, defined as Children’s Global Assessment Scale scores of under 30, was associated with both suicidal threats and acts. Violent acts were associated with both suicidal threats and acts in 2000, but not in 2011. Despite changes in treatment practices and shorter inpatient stays, the prevalence of suicidality in child and adolescent inpatient treatment remained unchanged in Finland in 2000 and 2011.