We prepared this study to determine the effect of cryoanalgesia on post-thoracotomy pain. In this double-blinded randomized clinical trial, 60 patients who underwent thoracotomy were divided into two groups (control and cryoanalgesia). Visual Analogue Scale (VAS, 0-10) was used for the measurement of severity of post-thoracotomy pain. It was classified into three categories: 0-1 (mild), 2-3 (moderate), and 4-10 (severe). Pethidine (0.5-1 mg/kg) was administered in case of need for both groups. Patients were visited at the hospital a week later, and were contacted by phone at the first, second, and third months post-operatively. Intensity of pain in the control group was higher than the cryoanalgesia group in all visits the follow-up period. On the second day, the frequencies of severe pain (4-10) were 33.3% and 0 in the control and cryoanalgesia groups, respectively. The mild pain on the seventh day was 13.3% and 83.3% in the control and cryoanalgesia groups, respectively (P < 0.01). Pethidine consumption was 151.6 ± 27 mg in the control group and 87.5 ±48 mg in the cryoanalgesia group on the first day post-operation (P < 0.001). Cryoanalgesia is a useful technique with not serious side effects in order to alleviate post-thoracotomy pain and reduce the need for opiate consumption.