Objectives. 1. To demonstrate clinical effectiveness of micronized palmitoylethanolamide-trans-polydatin combination in reducing endometriotic chronic pelvic pain (main objective); 2. To reduce other endometriotic-associated pain; 3. To assess the effects of this treatment in patient sub-groups; 4. To demonstrate that such therapy modifies natural history of the disease. Data sources. Systematic reviews of PubMed, SCIELO, Scopus, and AJOL, without regard to time frame and other limits. Study eligibility criteria. Randomized trials and observational studies reporting a visual analogue scale for pain or similar assessments at enrollment and at least at one follow-up in endometriotic patients. Study appraisal and synthesis methods: stringent, subjective, semi-quantitative assessment of study quality in relation to data availability and results exposure; additional assessment of study availability to meet meta-analysis objectives. Quantifying of mean improvement of visual analogue scale (or visual analogue scale-like) scores at enrollment and at a three month-follow-up. Interpreting data from a clinical point of view, according to generally accepted criteria. Results. Data were collected from 4 studies of poor quality (5 effect sizes). These were unable to satisfy objectives 3 and 4, and partially answered objective 2. In a heterogeneous sample of endometriotic patients with pain, the oral administration of micronized palmitoylethanolamide/trans-polydatin (400 mg/40 mg) twice a day for three months provided a clinically relevant improvement in chronic pelvic pain and dysmenorrhea while improving deep dyspareunia to a limited degree. No clinically relevant improvement was found for dyschezia. Conclusion. The combination of micronized palmitoylethanolamide/trans-polydatin appears to be a promising treatment for chronic pelvic pain and, possibly, other acute pain in endometrioic patients. More good-quality evidence on this treatment is warranted.