Investigated the incidence and severity of Posttraumatic Stress Disorder (PTSD) in childhood cancer using informant methodology. The parents of pediatric cancer patients (n = 30) and off-treatment survivors (n = 42) completed a modified version of the Posttraumatic Stress Disorder Symptom Scale (PSS) on their children (M age = 8.8: SD = 4.0), in addition to the Child Behavior Checklist (CBCL) and the Personality Inventory for Children (PIC). Medical treatment and demographic data were also collected for each child. The only variables that significantly identified the presence of symptoms of PTSD were being on treatment at the time of the evaluation or in the preparatory phase prior to bone marrow transplantation and not having received cranial irradiation. Results indicate that a full constellation of PTSD symptoms can occur in children over the course of cancer treatment. Within the off-treatment pediatric cancer survivors, however, the incidence of PTSD was no greater than epidemiological estimates from the general population. The concurrent validity of the PSS received support, and the results, while preliminary, suggest that extended periods of medical trauma during which emotional support is present may not excessively predispose children to PTSD.