Abstract Study question What are the test-retest reliability and the domain structures of the Dutch version of the PCOSQ and PCOSQOL in Dutch and Flemish women with PCOS? Summary answer The Dutch version of the PCOSQ and the PCOSQOL are reliable and can both be used to measure health-related quality of life (HRQoL) in PCOS. What is known already The polycystic ovary syndrome questionnaire (PCOSQ) is recommended to measure the quality of life in women with PCOS. The PCOSQ was developed in 1998 to complement generic health-related QoL instruments. The PCOSQ has been validated in Arabic, German, Chinese, and Swedish. Recent research suggested that the PCOSQ focuses on the physical impact of PCOS and that psychological, social, or environmental aspects are less represented. Therefore, the Polycystic Ovary Syndrome Quality Of Life Scale (PCOSQOL) was developed in 2018. Both questionnaires have not been validated in Dutch yet. Study design, size, duration A forward and backward translation was performed on the original English PCOSQ and PCOSQOL by two independent translators. PCOS patients were contacted with a request to complete both questionnaires (and some additional demographic questions) online in their home environment (T0). A test-retest design was applied to demonstrate stability over time by having all women complete the same questionnaires a second time (T1). Approval of the clinic’s Ethics Committee was obtained in both participating centres. Participants/materials, setting, methods Women of at least 18 years old, who were able to speak and write Dutch, and who were diagnosed with PCOS according to the Rotterdam criteria (ESHRE/ASRM, 2003) or according to the international evidence-based guideline for the assessment and management of PCOS (ESHRE, 2018) were eligible for the study. Women who were pregnant at T0 or T1 were excluded from the study. Participants were included between January and December 2021. Main results and the role of chance In total, 245 women were included in this study. The median age was 31 (19-54) years. For the PCOSQ, the Cronbach alpha statistic for the five domains ranged from 0.88 to 0.96 demonstrating good to excellent internal consistency. The Intra-class Correlation Coefficient (ICC) for the five domains was high to excellent ranging from 0.88 to 0.96. For the PCOSQOL, the Cronbach alpha ranged from 0.91 to 0.96 demonstrating excellent internal consistency. The ICC ranged from 0.91 to 0.96 for the four domains indicating excellent reliability. The factor analysis presented five domains of the PCOSQ and the original domain structure was partly confirmed. An extra domain for acne was included based on previous studies. Therefore, the Dutch version of the PCOSQ contained six domains: Weight, Body hair, Emotions, Infertility, Menstrual problems, and Acne. Based on the factor analysis, an extra domain was added to the original four domains of the PCOSQOL, which included items related to dealing with PCOS. Most women (70.6%) needed approximately 15 minutes to complete both questionnaires and had no preference for one of the two questionnaires (55.9%). Limitations, reasons for caution A limitation of our study could be that women with more PCOS complaints were more motivated to participate in this study. Therefore, potential selection bias should be taken into account. Wider implications of the findings The PCOSQ and PCOSQOL are disease-specific QoL measures for women with PCOS. The Dutch versions can be used in studies and in clinical settings (e.g. by nurses and midwives, counsellors, psychologists) to examine the impact of PCOS on QoL in Dutch and Flemish women. Trial registration number NA