The purpose of this study was to determine the prevalence of posttraumatic stress disorder (PTSD) in parents of children with cancer. Five questionnaires were administered to 104 parents, including a sociodemographic questionnaire, a traumatic events check list, the Structured Clinical Interview for DSM-IV PTSD and Major Depressive Disorder modules, and the self-rating instrument General Health Questionnaire-12. The prevalence of PTSD was 34.6%. The statistically significant tendency to develop PTSD were found in the female gender, better educational status, death of a loved one, previous history of psychiatric disorder, having a child with poorer prognosis, and the presence of radiotherapy in child's treatment. The vulnerable parents must receive psychosocial support.