Research question: Does the endometriosis diet positively affect quality of life (QoL) in women diagnosed with endometriosis? Design: A cross-sectional study was performed, recruiting women using the website and online peer platforms from the Dutch Endometriosis Society. In total, 211 women with a self-reported diagnosis of endometriosis were included in the study. They completed a questionnaire on the six QoL domains based on the conversation tool ‘My Positive Health’. Women who adhered to the endometriosis diet were compared with women who did not. A distinction was made between strict (score ≥8 on a scale of 0–10) and less strict adherence to the diet. Results: A significantly higher score was seen in all six QoL domains in women who adhered to the endometriosis diet (n = 90) compared with women who did not (n = 121) (range P < 0.001 to P = 0.043). Furthermore, women with strict adherence (n = 48) compared to less strict adherence (n = 42) reported significantly higher scores in all six QoL domains (range P = 0.005 to 0.05). Women diagnosed with endometriosis more than 10 years ago (n = 13) adhered to the endometriosis diet significantly less often than women that were diagnosed more recently (n = 163; range P = 0.005 to 0.046). Conclusion: The endometriosis diet was associated with a better QoL in Dutch women with endometriosis. Strict adherence showed higher QoL scores compared with less strict adherence. Therefore, more research is needed to clarify the mechanism of this beneficial effect and to identify facilitators and barriers to dietary adjustments in patients with endometriosis.