A pain after thoracotomy may result in a postoperative hypoventilation and lead to atelectases and pneumonia. This study was aimed to compare two analgesic regimens after posterolateral thoracotomy. 80 patients (40-70 years) undergoing thoracotomy were randomized to intercostal catheter analgesia (group A, n = 40) and intercostal nerve block (group B, n = 40). Patients in group A were given 20 mL of 0.5% bupivacaine injections twice a day by intercostal catheter. Intercostal nerve blockade was performed using 5 mL of 0.5% bupivacaine. Intercostal nerve in thoracotomy wound, nerves below and above thoracotomy wound was also injected. PaO2, PaCO2, FVC, FEV1 and visual analog pain scale (VAS) were obtained preoperatively, 24, 48 and 72 hours after operation. Postoperative complications were recorded at the patient discharge. Differences between groups were calculated using Mann-Whitney, KW test and chi square test. The arterial blood gas analyses did not show statistically significant change in any group and time according to the baseline values. FVC and FEV1 decreased significantly in both groups at first postoperative day according to baseline measurements. Patients in B group had significantly higher FEV1 values in the third postoperative day (73.05 +/- 11.25 in A vs. 83.50 +/- 9.17 in B group, p < 0.05). Intercostal catheter analgesia resulted in significantly lower postoperative VAS scores and reduced opioid requirement as compared to intercostal nerve blockade. No differences in the postoperative complications were observed between groups.