Background: People with severe mental illness are often excluded from trials related to Eye Movement Desensitisation and Reprocessing (EMDR) therapy. Principal concerns are that they may not tolerate treatment, might risk relapse or that psychotic symptoms may worsen. There is however building evidence of a traumatogenic etiology of psychosis that may benefit therapeutically from EMDR. Methods : A randomised exploratory trial with a waiting-list controlled pilot design was employed to conduct a prospective treatment and six-month follow-up study with an interim 10-week analysis. Participants with psychosis and reported history of trauma, were randomised into EMDR and Treatment as usual (TAU) groups. The primary measure was the Impact of Events Outcome Scale (IES) with secondary outcome measures of Positive and Negative Symptoms of Psychosis (PANSS), PTSD Checklist (PCL-C), and subjective Quality of Life (MANSA). Results: IES scores showed significant improvements in the EMDR group (n=24) compared to the TAU group (n=12) at 10 weeks and at six months (p<0.05). There were significant improvements in PCL-C and PANSS negative symptoms scores associated with treatment (p<0.05). All other scales too showed positive trends. No adverse events were noted during the study period. Conclusions: This is the first study demonstrating safety and effectiveness of EMDR for people with psychosis and trauma in British routine psychiatric settings. Benefits were found to last at least six months. A novel approach to treat psychosis in routine community settings is suggested. Larger trials and economic analyses are indicated to further investigate the place of EMDR for psychosis.Cornwall Partnership NHS Foundation Trust