Little direct evidence supports any particular treatment for posttraumatic stress disorder (PTSD) in people with schizophrenia, forensic histories, and/or multiple comorbidities. This trial assesses the efficacy and risks of eye movement desensitization and reprocessing (EMDR) for people with PTSD and psychotic disorders receiving forensic care, including inpatients and prisoners. Single-blind randomized controlled trial comparing EMDR therapy to wait-list (routine care) in forensic-treated adults with psychotic disorders and PTSD. The primary outcome was clinician-rated PTSD symptoms. Secondary outcomes included participant-rated PTSD symptoms, psychotic symptoms, social functioning, disability level, self-esteem, depressive symptoms, posttraumatic cognitions, complex posttraumatic difficulties, and adverse events. Blinded investigators assessed outcomes at baseline, and after 10 weeks and 6 months. Analysis of the primary outcome was by a mixed linear model. Twenty-four participants were randomized, recruitment being hindered by COVID-19 restrictions. Clinician Administered PTSD Scale mean (SD) scores after 6 months were lower (better) in the EMDR group, 21.3 (13.3), compared with the control group, 31.5 (20.7). The point estimate [95% CI] difference, averaged over two measurement times, was 11.4 [1.3, 21.4], p = .028, favoring EMDR. Self-esteem increased in the EMDR group and depressive symptoms and disability reduced. There were no statistically significant differences in psychotic symptoms or adverse events, although point estimates favored EMDR. This is the first EMDR trial in mental health inpatient, forensic, or custodial settings, where PTSD is common. There were improvements in PTSD and other symptomatology consistent with EMDR being a safe and effective treatment for PTSD in these settings. (PsycInfo Database Record (c) 2024 APA, all rights reserved).