Imagery Rehearsal Therapy (IRT) has been shown to be efficacious in reducing nightmares, but the treatment has not been well-studied in veterans. The effectiveness of IRT was assessed from a chart review of veterans seeking outpatient treatment for chronic, trauma-related nightmares. Of those offered IRT, veterans who completed a full course of treatment for PTSD in the past year were more likely to initiate treatment. However, completion of IRT was not related to previous treatment, demographic variables, or nightmare severity reported at the first treatment session. Treatment completers reported significant reductions in nightmare frequency and intensity, severity of insomnia, and subjective daytime PTSD symptoms. Insomnia and PTSD symptoms, on average, were below clinical cutoffs following treatment, and 23% of patients showed a complete treatment response (< or =1 nightmare/week). Findings suggest IRT may be an effective short-term treatment for nighttime and daytime PTSD symptoms among veterans who complete a full course of treatment.