The application of a trauma model to understanding the impact of life-threatening illness has been informative. In the case of childhood cancer patients, it appears clear that a full PTSD syndrome is not the normative response either during or after treatment. Some aspects of cancer diagnosis and treatment, however, are experienced as traumatic by a subset of children, some of whom report symptoms of posttraumatic stress. There is some evidence that children may respond to cancer treatment as a repeated trauma, with the result of more subtle changes in affect modulation, world view, and interpersonal relationships. This area requires further investigation. The trauma model is also useful in understanding parental responses to childhood cancer. The epidemiologic data to date regarding posttraumatic stress symptoms in parents of childhood cancer survivors is consistent with the trauma literature regarding responses to moderate-magnitude traumatic exposure. These findings have important implications for clinical interventions for families of childhood cancer patients. More research is needed in the prediction and prevention of the long-term distress reported by so many parents of children who have undergone successful treatment for life-threatening illness.