Patients with double primary cancer (DPC) of the ovary and endometrium are considered to have a better prognosis than patients with only epithelial ovarian cancer (EOC). The aim of this study was to clarify the difference in prognosis by comparing clinicopathologic characteristics and survival. From the population-based database of the nationwide Netherlands Cancer Registry, women diagnosed between 1996 and 2006 with EOC were identified. Within this database of all EOC patients in 11 hospitals, the DPC patients were identified. Differences in characteristics between EOC-only and DPC patients were tested using Pearson χ tests and t-tests. Differences in overall survival were analyzed by Kaplan-Meier survival analyses and log-rank tests. Multivariable Cox regression analyses were performed to study the factors that influence survival. Among 1105 EOC patients, 29 (2.6%) DPC patients were identified. DPC patients were more often premenopausal (P<0.01), in the early stage of disease (P<0.01), and more often had low-grade endometrioid tumors. Overall survival was better for DPC patients (P=0.004), but after stratification for stage the overall survival was similar. In multivariable analysis, DPC patients did not show a favorable prognosis after adjustment for age, disease stage, histology, tumor grade, and residual tumor after surgery. DPC patients seem to constitute a prognostically favorable group among EOC patients; however, after correction for age, stage, histology, tumor grade, and residue, survival is similar. This study shows how important it is for clinicians to distinguish DPC from metastatic diseases.