The first reference to chronic post-thoracotomy pain was in 1944 by United States Army surgeons who noted ‘chronic intercostal pain’ in men who had thoracotomy for chest trauma during the Second World War [1]. Chronic post-thoracotomy pain is defined by the International Association for the Study of Pain as pain that recurs or persists along a thoracotomy incision at least 2 months following the surgical procedure [2]. It is typically burning and dysesthetic in nature and has many features of neuropathic pain [3, 4]. Post-thoracotomy pain also may result, at least in part, from a non-neuropathic origin (myofascial pain) [5]. Several studies have estimated the incidence of post-thoracotomy pain as ranging from 25–60% which makes postthoracotomy pain the commonest complication of thoracotomy. Thoracotomy, along with limb amputation, is considered to be the procedure that elicits the highest risk of severe chronic postoperative pain [6]. This chapter outlines the prevalence of this condition and then discusses the potential etiological factors and treatment strategies and possible future research.