In the present study the prevalence of nightmare disorder (ND) was examined in patients with dissociative disorders (DD), and comparison was made between those with ND and those without nightmares in terms of clinical characteristics. The 30 patients with DD (5 male and 25 female) were recruited over 12 months in the Yuzuncu Yil University Research Hospital Department of Psychiatry. The subjects were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders (4th edn) criteria for ND. The Dissociative Experiences Scale, Beck Depression Inventory, and a semistructured interview schedule for childhood traumatic events were administered to the subjects. A 57% prevalence of ND was found among patients with DD. Among patients with DD, those with ND had a higher rate of self-mutilative behavior, a history of suicide attempt in the last year, and comorbidity with borderline personality disorder than those without ND. Nightmares or dreams should be considered in the therapy of DD patients.