Aims. To assess the efficacy of a micronized-palmitoylethanolamide-polydatin (m-PEA-Pol) based product on chronic pelvic pain and severity of other symptoms in interstitial cystitis/bladder pain syndrome (IC/BPS) patients refractory to conventional therapies. Methods. A pilot, open-label bicentric study was carried out involving 32 IC/BPS patients. Chronic, oral m-PEA-Pol treatment lasted 6 months. Bladder pain was evaluated using the visual analog scale, while changes from baseline in other urinary symptoms were evaluated by means of the O’Leary-Sant Interstitial Cystitis Symptom and Problem Index and the Pelvic Pain and Urgency/Frequency (PUF) symptom scale questionnaires. The generalized linear mixed model was used to evaluate significant mean changes across time. Results. A significant and progressive reduction of pain intensity was observed during m-PEA-Pol treatment (p<0.0001 for reduction over time). The effect was associated with a reduction in severity of patients’ symptoms evaluated with the O’Leary-Sant questionnaire (p=0.0110 and p=0.0014 for cystitis symptoms and problem mean scores, respectively) and the PUF scale (p=0.0163 and p=0.0005 for symptom and bother mean scores, respectively). m-PEA-Pol therapy elicited a significant reduction over time in the urinary frequency evaluated with voiding diary (p=0.0005) and a small but not significant improvement of bladder capacity. Conclusions. These data highlight the potential benefit of m-PEA-Pol in patients with rare pathology such as IC/BPS and confirm the good safety profile of micronized PEA-based products.