Aim: Cancer treatment involves long-term therapy and follow-up, with mental disorders (MD) often affecting the treatment process. Hence, in this study, we retrospectively analyze cases involving gynecologic cancer with MD and clarify the relationship between psychosis and cancer prognosis. Methods: Patients with both gynecologic cancer and MD from January 2003 to August 2016 were recruited in this study. Cases were limited to those whose MD had been diagnosed before their cancer. Control patients without MD were also analyzed. Both cases and controls were adjusted for age, cancer type, and cancer stage. Results: A total of 54 patients with gynecologic cancer and MD, as well as 108 controls without MD, were included. The median age of the patients was 52 years. Details regarding cancer type were as follows: 11 ovarian cancers, 26 uterine corpus cancers and 17 cervical cancers. Among these, 25 schizophrenia cases, 15 depressive disorders, 4 bipolar disorders and 10 other MD were recorded. No significant differences in the 5-year survival rate were found between patients and controls. In advanced-stage cervical cancer, however, the prognosis was significantly poor given the low rate of initial treatment completion. Moreover, patients with advanced-stage cervical cancer had significantly lower chemotherapy completion rates compared to those with other gynecologic malignancies. Conclusion: Mental disorders do not affect the prognosis of gynecologic cancers, except for advanced cervical cancer. Accordingly, improving the low rate of initial treatment completion seems to be a focal point for better prognosis in advanced cervical cancer.