Background: Thoracic epidural analgesia is associated with a high rate of postoperative urine retention (POUR). Auriculotherapy can reduce visceral dysfunction and can be helpful in anesthesiology and pain control. The aim of this study was to test the efficacy of preoperative auriculotherapy to decrease the occurrence of POUR. Methods: This single-center, double-blinded, two-arm randomized study was performed between January 2015 and May 2016 in a tertiary care university hospital. Male patients scheduled for an elective lung surgical procedure under combined general anesthesia and thoracic epidural analgesia were included. Auriculotherapy (A group) was performed once the patient was under general anesthesia with five semi-permanent needles inserted in both ears at the “Shen Men”, “bladder”, “pelvic parasympathetic”, “anterior hypothalamus”, and “frontal lobe” points). Five small round patches of adhesive pads were positioned bilaterally at the same points in the Control group (C group). The main outcome measure was the requirement for bladder catheterization during the day and the first night following surgery. Results: Fifty-three patients were randomized and 25 analyzed in each group. Requirement for bladder catheterization was different between groups: 24 C group patients (96%) and 18 A group patients (72%) (p=0.049, Fisher exact test; Odds Ratio=0.11 [0.01–0.95]. The number of patients needed to treat with auriculotherapy to avoid one case of bladder catheterization was four. No adverse effect was observed due to auriculotherapy. Conclusion: This study demonstrates that auriculotherapy is a safe and useful technique reducing POUR in thoracotomy patients benefiting from thoracic epidural analgesia.