BACKGROUND: This study was performed to evaluate the effects of intercostal nerve block added in intravenous patient-controlled analgesia (IV-PCA; PCA) on pain, pulmonary function and the movement of the ipsilateral arm after a thoracotomy. METHODS: Forty five patients undergoing elective thoracotomy were randomly allocated into one of three groups. The groups were divided as follows: PCA, ICB-PCA (PCA and intercostal nerve blocks by direct injection of 5 ml of 0.2% bupivacaine into the intercostal spaces of two upper and two lower segments around the surgical incision) and IM groups. For the PCA, the patients that received PCA, were administered IV bolus of 0.1 mg/kg of nalbuphine followed by PCA with 0.1% nalbuphine (basal rate 0.5 ml/hr, bolus dose 1 mg and lockout interval 8 minutes). In each group, VAS score, the inspiratory capacity and the movement of the ipsilateral arm were checked postoperatively at 6, 24, 48 and 72 hours. RESULTS: Inspiratory capacity was decreased less in ICB-PCA group (P<0.05) at 6 hour, but after 24 hour, there were no differences between the groups. The analgesic effect was significantly better in ICB-PCA group as compared to the PCA or IM groups (P<0.05). Furthermore, arm motion limitation after operation was the least in ICB-PCA group (P<0.01). CONCLUSION: Intraoperative intercostal nerve blocks added in PCA has a transient improvement of pulmonary function, and also provide better analgesia and improved ipsilateral arm motion after a thoracotomy than in PCA or IM analgesia. The authors recommend adding intercostal nerve block for patients undergoing thoracotomy who receive IV-PCA.