We present three cases of post-traumatic stress disorder (PTSD) that occurred in patients with gynecologic cancers. Case 1 and 2 had ovarian cancer and case 3 had endometrial cancer. The patients developed anxiety, difficulty in sleeping, and complaints of various discomforts after their diagnosis. On consulting with psychiatrists, PTSD was diagnosed based upon the DSM-IV classification. In cases 1 and 2, the symptoms worsened during the patients' primary treatment and interfered with their ability to continue the treatment. Psychiatric interventions were provided making it possible to complete their treatment. In case 3, the patient needed psychiatric intervention because of her psychological distress during her treatment. She was finally diagnosed as having PTSD. There are few reports regarding PTSD occurring in gynecologic cancer patients. However, attention should be given to the symptoms of these disorders so that patients may complete their standard therapies.