This study aims to determine the test–retest reliability and to confirm the domain structures of the Dutch version of the modified polycystic ovary syndrome questionnaire (mPCOSQ) and the Polycystic Ovary Syndrome Quality of Life Scale (PCOSQOL) in Dutch and Flemish women with Polycystic Ovary Syndrome (PCOS). PCOS patients were contacted with a request to complete both questionnaires (including additional demographic questions) online in their home environment on T0 and on T1. The study was approved by the Ethics Committee of Erasmus Medical Centre and of Ghent University Hospital. In this study, 245 participants were included between January and December 2021. The mPCOSQ has excellent internal consistency (α: 0.95) and a high to excellent Intraclass Correlation Coefficient (ICC) for all six domains (ICC: 0.88–0.96). The PCOSQOL demonstrates excellent internal consistency (α: 0.96) and ICC (ICC: 0.91–0.96) for all four domains. The original six-factor structure of the mPCOSQ is partly confirmed. An extra domain is added to the PCOSQOL which included coping items. Most women have no preference for one of the two questionnaires (55.9%). In conclusion, The Dutch mPCOSQ and PCOSQOL are reliable and disease-specific QoL measures for women with PCOS. Both questionnaires are recommended for clinical practice.