Post-thoracotomy pain leads to patient discomfort, pulmonary complications, and increased analgesic use. Intercostal nerve injury during thoracotomy or its entrapment during closure can contribute to post-thoracotomy pain. We hypothesized that a modified technique of posterolateral thoracotomy and closure, preserving the intercostal neurovascular bundle, would reduce acute and chronic post-thoracotomy pain. We randomized 90 patients undergoing posterolateral thoracotomy for pulmonary resection at a tertiary level oncology center to standard posterolateral (control arm) or modified nerve-sparing thoracotomy. All patients received morphine via patient-controlled analgesia pumps. The primary outcome was the worst postoperative pain score in the first 3 postoperative days. Secondary outcomes included the average pain score and analgesic requirements in the first 3 postoperative days and the incidence of post-thoracotomy pain 6 months after surgery. No significant differences were seen between the groups in acute or chronic post-thoracotomy measured by the numeric rating scale. There was no difference seen in the worst (mean) postoperative pain scores (3.71 vs 3.83, difference 0.12; 99% confidence interval [CI], -0.7 to +0.9; P = .7), average (mean) pain scores in the first 3 postoperative days (1.77 vs 1.85, difference 0.08; 99% CI, -0.4 to +0.6; P = .69), mean consumption of morphine (mg/kg) (1.45 vs 1.40, difference -0.05; 99% CI, -0.4 to +0.3; P = .73), or incidence of chronic postoperative pain (37.8% vs 40%, difference 4.9%; 99% CI, -22.8 to +30.7%; P = .73). The modified nerve-sparing thoracotomy technique does not reduce post-thoracotomy pain compared with standard posterolateral thoracotomy.