Abstract Background Initial studies have shown that posttraumatic stress disorder (PTSD) can be effectivelytreated in patients with a psychotic disorder. These studies however used adapted treatment protocols, avoided direct exposure to trauma related stimuli or preceded treatment with stabilizing techniques making treatment considerably longer in duration. Method An open trial in which adult subjects with a psychotic disorder and a comorbid PTSD ( n  = 27) received a maximum of six Eye Movement Desensitization and Reprocessing (EMDR) therapy sessions. PTSD symptoms, psychotic symptoms and additional symptoms were assessed at baseline and end-of-treatment. Results The dropout rate was 18.5 percent (five subjects). Only five of the twenty-two completers (22.7%) still met criteria for PTSD after treatment. PTSD symptoms, auditory verbal hallucinations, delusions, anxiety, depression, and self-esteem all improved significantly. Paranoid ideation and feelings of hopelessness did not improve significantly. Treatment did not lead to symptom exacerbation in subjects. There were no adverse events, such as suicide attempts, self-mutilation, aggressive behavior or admission to a general or psychiatric hospital. Conclusions This pilot study shows that a short EMDR therapy is effective and safe in the treatment of PTSD in subjects with a psychotic disorder. Treatment of PTSD has a positive effect on auditory verbal hallucinations, delusions, anxiety symptoms, depression symptoms, and self-esteem. EMDR can be applied to this group of patients without adapting the treatment protocol or delaying treatment by preceding it with stabilizing interventions.