Background: Patients undergoing thoracotomy frequently experience acute pain and chronic post-thoracotomy pain (CPTP). There are few articles relating to the investigations on the effects of preoperative single-dose thoracic paravertebral block (PSTPVB) on acute pain and CPTP. We tested the hypothesis that adding PSTPVB to intravenous (IV) patient-controlled analgesia (PCA) would reduce acute pain scores and decrease the incidence and intensity of CPTP. Methods: Fifty-six patients undergoing elective thoracotomy were randomized to receive PSTPVB in addition to IV PCA (group T) or IV PCA alone (group C). A single 20-mL injection of 0.50% ropivacaine plus 10 mg dexamethasone in saline was administered preoperatively under ultrasound guidance; sufentanil was used for IV PCA. The acute pain intensity at rest and at coughing based on verbal rating scale, postoperative sufentanil consumption, and complications were evaluated at 6, 24, 48, and 72hours after surgery. The incidence and intensity of CPTP were evaluated at 3 months after surgery. Results: Group T had significantly less acute pain compared with group C at all measurement times both at rest and at coughing (P<.05). The PCA cumulative sufentanil consumption, complications, and the incidence of CPTP between the 2 groups was not statistically significant (P>.05). The intensity of CPTP was significantly higher in group C than in group T (P<. 05). Conclusion: This study indicated that adding PSTPVB to IV PCA improved acute postoperative pain and chronic pain in patients undergoing thoracotomy, but did not reduce the incidence of CPTP.