Chronic post-thoracotomy pain (CPP) is a vexing clinical problem whose management has received scant attention. In order to identify the risk factors associated with CPP and determine the optimal treatment, the records of 238 consecutive patients who underwent thoracotomy were reviewed. CPP was defined as discomfort requiring the regular administration of analgesics that continued more than three months following surgery. CPP was present in 25 (11%) patients: 10/20 (50%) chest wall resections, 5/25 (20%) pleurectomies, 10/193 (5%) pulmonary resections. Among the 23 patients who required preoperative narcotics, 12 (52%) developed CPP. Improved pain control and decreased narcotic use was achieved via the administration of nonsteroidal anti-inflammatory medication and tricyclic anti-depressants. In addition, 10/25 patients required 11 pain procedures: trigger-point injection, intercostal blocks, injections of epidural steroids, stellate ganglion block. Recurrent pain occurred in 20 patients following initial control. All were found to have tumor regrowth. We conclude that CPP occurs more commonly following chest-wall resection and pleurectomy, and that preoperative narcotic use is a predictor of CPP. Worsening pain following initial relief should prompt a vigorous search for recurrent cancer.