Objective To compare the effect of intravenous and epidural analgesia on postoperative complications after abdominal and thoracic surgery. Methods A literature search was conducted by using computerized database on PubMed, EBSCO, Springer, Ovid, and CNKI from 1985 to Jan 2009. Further searches for articles were conducted by checking all references describing postoperative complications with intravenous and epidural anesthesia after abdominal and thoracic surgery. All included randomized controlled trials (RCTs) were assessed and data were extracted by the standard of Cochrane systematic review. The homogeneous studies were pooled using RevMan 4.2.10 software. Results Thirteen RCTs involving 3 055 patients met the inclusion criteria. The results of meta-analyses showed that, a) pulmonary complications and lung function: patient-controlled epidural analgesia can significantly decrease the incidence of pneumonia (RR=0.66, 95%CI 0.53 to 0.83) and improve the FEV1 (WMD=0.17, 95%CI 0.05 to 0.29) and FVC (WMD=0.21, 95%CI 0.1 to 0.32) of lung function after abdominal and thoracic surgery, but no differences in decreasing postoperative respiratory failure (RR=0.77, 95%CI 0.58 to 1.02) and prolonged ventilation (RR=0.75, 95%CI 0.51 to 1.13) compared with intravenous analgesia; b) cardiovascular event: epidural analgesia could significantly decrease the incidence of myocardial infarction (RR=0.58, 95%CI 0.35 to 0.95) and arrhythmia (RR=0.64, 95%CI 0.47 to 0.88) than the control group, but could not better reduce the risk of heart failure (RR=0.79, 95%CI 0.47 to 1.34) and hypotension (RR=1.21, 95%CI 0.63 to 2.29); and c) Other complications: epidural and intravenous analgesia had no difference in decreasing the risk of postoperative renal insufficient (RR=0.78, 95%CI 0.53 to 1.14), gastrointestinal hemorrhage (RR=0.78, 95%CI 0.49 to 1.23), infection (RR=0.89, 95%CI 0.70 to 1.12) and nausea (RR=1.03, 95%CI 0.38 to 2.81). Conclusions Epidural analgesia can obviously decrease the risk of pneumonia, myocardial infarction and severe arrhythmia, and can improve the lung function after abdominal or thoracic surgery.