This study used a self-report measure of posttraumatic stress (the Posttraumatic Stress Disorder Reaction Index) to evaluate 64 pediatric leukemia survivors age 7-19 years and their parents (mothers n = 63, fathers n = 42). Based upon normative data for the Reaction Index, 12.5% of the survivors, 39.7% of the mothers, and 33.3% of the fathers reported symptoms consistent with a severe level of posttraumatic stress. The data indicate that a substantial subset of pediatric cancer survivors and their parents experience severe symptoms that can be understood within a posttraumatic stress model. The data are discussed with regard to pediatric follow-up care for cancer survivors, as well as in terms of preventive steps that could be taken to lessen the traumatic aspects of pediatric cancer treatment.