Background: Chronic post-thoracotomy pain (CPTP) consists of different types of pain. Some characteristics of CPTP are the same as those of recognized neuropathic pain syndromes. Objective: We aimed to determine the safety and efficacy of gabapentin (GP) in comparison to naproxen sodium (NS) in patients with CPTP. Methods: Forty consecutive patients with CPTP after posterolateral/lateral thoracotomy were prospectively evaluated. Twenty patients were given GP and another 20 were given NS treatment. Visual Analogue Scale (VAS) and the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) scorings were performed pretreatment (day 0) and on the 15th, 30th, 45th and 60th days. Adverse events were questioned. The mean ages were 45.7 +/- 14.9 and 49.8 +/- 15.2 years and the mean durations of pain were 3.8 +/- 0.9 and 3.8 +/- 1.1 months, respectively. Results: The mean pretreatment VAS scores (VAS(0)) were 6.4 +/- 0.6 and 6.8 +/- 0.6, the mean pretreatment LANSS scores (LANSS(0)) were 18.85 +/- 1.6 and 20.75 +/- 2.6 in GP and NS groups, respectively (p > 0.05). Minor adverse events which did not mandate discontinuation of treatment were observed in seven patients (35%) in the GP and in four patients (20%) in the NS group. The number of patients with a VAS score <5 at the latest follow-up (VAS(60) < 5) was 17 (85%) and 3 (15%) in GP and NS groups, respectively (p < 0.001). Seventeen patients (85%) in the GP and 0 patients (0%) in the NS group had a LANSS score <12 at the latest follow-up. Conclusion: Gabapentin is safe and effective in the treatment of CPTP with minimal side effects and a high patient compliance. These results should be supported with multidisciplinary studies with larger sample sizes and longer follow-ups. (c) 2007 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.