Research has shown that posttraumatic stress disorder (PTSD) is a highly prevalent diagnosis for psychiatric patients, yet individualized care and treatment is limited in the inpatient acute care sector. Two case studies are presented which examine the use of Exposure, Relaxation, and Rescripting Therapy (ERRT) for chronic trauma-related nightmares, within a private acute care inpatient psychiatric hospital setting. ERRT is empirically supported with efficacy for veteran and civilian populations, however no research to date has been conducted with psychiatric inpatients. Two participants diagnosed with PTSD, suffering distressing trauma-related nightmares, completed ERRT over three sessions during their psychiatric hospital admission, with the aim of reducing the frequency and severity of nightmares and related psychological symptoms. PTSD, depression, sleep quality and quantity, and nightmare frequency and related distress, were measured pre-treatment, during treatment, and follow-up at one, 3 and 6 months. Only one participant reported ongoing nightmares by the third week of the intervention, with both participants reporting an absence of nightmares at the one and 3-month follow-ups, but mixed results by the 6-month follow-up. One participant also reported a reduction in PTSD symptoms and a mild improvement in depression. The results offer some preliminary support for the provision of ERRT for the treatment of trauma-related nightmares for psychiatric inpatients.