Purpose: Post-traumatic stress disorder (PTSD) rates among hospitalised adolescents are between 21% and 32%, and there is a lack of evidence-based interventions for this population. Trauma-focused cognitive behaviour therapy (TF-CBT) is an evidence-based intervention for children and adolescents with PTSD; however, it has not been implemented in an acute adolescent inpatient unit. This study examines the implementation of an intensive form of TF-CBT in an adolescent inpatient unit. Method: An uncontrolled open trail study was conducted where 15 adolescents diagnosed with PTSD were treated with an intensive form of TF-CBT. Measures used were the University of California, Los Angeles’ (UCLA) PTSD Reaction Index for Diagnostic and Statistical Manual of Mental Disorders (4th ed., Adolescent Version; DSM-IV-Adolescent Version), the National Stressful Events Survey PTSD Short Scale (NSESSS) and the Children’s Global Assessment Scale (CGAS) Results: Adolescents received an average of nine sessions of TF-CBT over a period of 28 days. The average NSESSS on admission was 23.73 and 8.27 at discharge; the CGAS average on admission was 19 and on discharge was 48.7; both were statistically significant changes. Conclusion: Preliminary findings support the use of an intensive form of TF-CBT to treat adolescents with PTSD admitted to acute adolescent inpatient units indicating the need for further research in this area.