This study evaluated the benefits of add-on hypnotherapy in patients with chronic post-traumatic stress disorder (PTSD). Thirty-two PTSD patients treated by selective serotonin reuptake inhibitor antidepressants and supportive psychotherapy were randomised to two groups: 15 patients in the first group received Zolpidem 10 mg nightly for 14 nights, and 17 patients in the hypnotherapy group were treated by symptom-oriented hypnotherapy twice-a-week, 1.5-h sessions for 2 weeks. All patients completed the Stanford Hypnotic Susceptibility Scale, Form C, Beck Depression Inventory, Impact of Event Scale, and Visual Subjective Sleep Quality Questionnaire before and after treatment. There was a significant main effect of the hypnotherapy treatment with PTSD symptoms as measured by the Post-Traumatic Stress Disorder Scale. This effect was preserved at follow-up 1 month later. Additional benefits for the hypnotherapy group were decreases in intrusion and avoidance reactions and improvement in all sleep variables assessed.