The characteristics of nightmares of 48 male U.S. Vietnam war veterans with combat-related posttraumatic stress disorder (PTSD), as well as revised dream scripts developed in the course of Imagery Rehearsal therapy, were examined in relation to pretreatment symptomatology and treatment outcome. Features, content, and themes of nightmares and rescripted dreams were coded by 2 independent raters. Nightmares were replete with scenes of death and violence and were predominantly replays of actual combat events in which the veteran was under attack and feared for his life. Although addressing or resolving the nightmare theme with rescripting was associated with a reduction in sleep disturbance, references to violence in the rescripted dream were related to poorer treatment outcome in nightmare frequency; B = 5.69 (SE = 1.14). The experience of olfactory sensations in nightmares, a possible index of nightmare intensity, was also related to poorer treatment response; B = 2.95 (SE = 1.06). Imagery rehearsal for individuals with severe, chronic PTSD and fairly replicative nightmares may be most effective when the rescripted dream incorporates a resolution of the nightmare theme and excludes violent details.