This study investigated whether diagnosis and treatment of breast cancer produced posttraumatic stress disorder (PTSD) in adult women. One hundred sixty women with early stage node-negative breast cancer completed self-report questionnaires and underwent a full diagnostic assessment (Structured Clinical Interview for DSM-III-R). PTSD symptoms were common; however, only 3% of the women interviewed met stringent criteria for cancer-related PTSD in the 4-12 months following the completion of their medical treatment. Thus, breast cancer produced considerable distress, but low rates of PTSD, and may not fit well as a Criterion A stressor event for PTSD. Caution is urged for an assumption of a PTSD diagnosis based on self-reported symptoms.