Patients often experience moderate to severe postoperative pain, especially during the first hours after hepatectomy. Systemic opioids given with patient-controlled analgesia has be used after hepatectomy in many medical center(Aubrun, Monsel et al. 2001; Aubrun, Salvi et al. 2005), but the analgesic effect can be limited and undesirable side effects may occur. A case report described that right thoracic paravertebral block reduced pain and analgesic requirements after right lobe hepatectomy(Ho, Karmakar et al. 2004). Compared with epidural analgesia, thoracic paravertebral block probably carries a much lower risk of spinal haematoma in the presence of moderate haemostatic deficiencies (Richardson and Lonnqvist 1998; Karmakar 2001). We therefore designed a prospective, randomized, subject and assessor blinded, parallel-group, placebo controlled study to test the hypothesis that continuous right thoracic paravertebral analgesia decreases opioid consumption during the first 24 h after right lobe hepatectomy in patients receiving i.v. patient-controlled analgesia (PCA) with sufentanil.