Posttraumatic nightmares are considered as a reexperiencing symptom of the DSM-IV posttraumatic stress disorder (PTSD) diagnosis. Different types of posttraumatic nightmares, however, may differ in their relation to psychopathology. Thirty-two children were longitudinally assessed 10 days, 2 months, and 6 months after traffic accidents. Occurrence and characteristics of nightmares were examined and their relation to psychopathology assessed. Thirty-four percent of children reported posttraumatic nightmares during at least one assessment. Exact replicative nightmares at baseline assessment predicted PTSD symptoms 2 and 6 months postaccident, but not depressive symptoms. Exact replicative nightmares revealed the strongest cross-sectional association with trauma-specific psychopathology but not with depression. The authors conclude that posttraumatic nightmares--especially exact replicative ones--may be closely related to psychopathological mechanisms of posttraumatic stress in children.